AlanH

955 reputation

219

bio	website	math.stackexchange.com/users/…
	location	Antarctica
	age	77
visits	member for	8 months
	seen	1 hour ago
stats	profile views	169

Self-learning mathematics. Many thanks to those who make time to help others on the site.

	955 reputation	bio	website	math.stackexchange.com/users/…	visits	member for	8 months
219 badges		location	Antarctica		seen	1 hour ago

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71 Questions

views newest activity votes

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answers

435

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Recurrence relation for the number of $n$-digit ternary sequences with no consecutive $1$s or $2$s

combinatorics recurrence-relations

mar 23 at 2:04 André Nicolas 168k

votes

answers

334

views

Discretization of Inhomogeneous Dirichlet Boundary Conditions for 2D Poisson's Equations

pde

mar 30 at 4:15 AlanH 955

votes

answers

293

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If an integer is divisible by 8 and 15, then the integer also must be divisible by which of the following?

homework elementary-number-theory divisibility

jan 25 at 0:02 AlanH 955

votes

answers

223

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How is this a property of Pascal's triangle?

combinatorics binomial-coefficients

dec 26 at 20:49 Jair Taylor 1,550

votes

answers

173

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Finding the coefficient of $x^{25}$ in $(1 + x^3 + x^8)^{10}$?

combinatorics generating-functions

feb 19 at 12:03 Tim Monahan 291

votes

answers

163

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Proof involving Stirling numbers of the second kind

combinatorics stirling-numbers

jan 6 at 3:59 Mike Spivey 26.1k

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156

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I can't figure out this combinatorics problem… Or at least why my solution doesn't work.

probability combinatorics

mar 23 at 3:43 AlanH 955

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144

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Combinatorial proof involving factorials

combinatorics

feb 9 at 14:43 Brian M. Scott 161k

vote

answer

136

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Number of integer solutions to a system of equations

combinatorics elementary-number-theory

feb 4 at 0:45 user17762 78.4k

votes

answers

131

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How to simplify this equality (factorials)?

sequences-and-series factorial

apr 4 at 13:18 julien 25.6k

votes

answer

125

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Finding variance of joint probability function of discrete random variables

probability probability-distributions

mar 6 at 5:16 AlanH 955

votes

answers

121

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When does $az + b\bar{z} + c = 0$ represent a line?

complex-analysis complex-numbers

apr 30 at 6:20 Georges Elencwajg 46.2k

votes

answers

119

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How to verify method used to solve integral was actually the fastest?

integration soft-question recreational-mathematics contest-math

mar 28 at 1:44 ephedyn 38

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answers

118

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Using $\gcd(a,b)$ to find gcd of other values $\gcd(a^2,b)$ and $\gcd(a^3,b)$

elementary-number-theory

may 12 at 0:16 vonbrand 7,071

votes

answers

117

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How many ways are there for 10 people to have five simultaneous telephone conversations?

combinatorics

feb 1 at 8:40 Marc van Leeuwen 25.7k

votes

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109

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Pigeon-hole Principle: Does this proof have a typo?

combinatorics

dec 20 at 1:08 Brian M. Scott 161k

votes

answers

108

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No. of ways to arrange letters of a word (with repetition)

combinatorics

feb 3 at 4:00 AlanH 955

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107

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General counting problem. Not sure how to proceed.

combinatorics

jan 18 at 4:27 hardmath 7,214

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103

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I've come up with two solutions to this problem, and I don't know which is correct.

combinatorics

jan 13 at 2:29 AlanH 955

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answers

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Solving functional equation for generating function

combinatorics recurrence-relations generating-functions

apr 11 at 7:59 Brian M. Scott 161k

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answers

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Integer solutions

combinatorics diophantine-equations partitions

feb 3 at 5:06 AlanH 955

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answers

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Finding coefficient of generating function

combinatorics generating-functions

mar 24 at 22:26 AlanH 955

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answers

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Using generating function to find number of ways to distribute $r$ objects

combinatorics generating-functions

feb 26 at 9:23 AlanH 955

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Is there something faulty about this statement?

elementary-number-theory solution-verification

may 3 at 23:37 marty cohen 7,519

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answers

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Grasping the definition of open and closed sets

general-topology analysis metric-spaces solution-verification

mar 30 at 2:47 AlanH 955

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answer

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What can we say about the order of a group given the order of two elements?

abstract-algebra group-theory finite-groups divisibility

2d ago Alexander Gruber♦ 15.7k

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answers

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Open sets in $\Bbb{R}^2$ and $\Bbb{R}^3$

analysis

5h ago dls 1,153

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answer

views

Combinatorial proof. What is this question asking?

combinatorics

feb 12 at 1:00 AlanH 955

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answers

views

Finding a closed form expression for this sum [duplicate]

combinatorics binomial-coefficients power-series

apr 13 at 3:32 Sasha 41.6k

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answers

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Functional equations and generating functions

combinatorics recurrence-relations generating-functions

apr 9 at 23:35 robjohn♦ 63k