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location Madrid, Spain
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visits member for 3 years, 9 months
seen Aug 24 at 20:51

Apr
17
answered Burgess on quadratic residues and non-residues
Feb
21
revised Is it a bad idea to use a Sieve of Eratosthenes to find all primes up to very large N?
added 1962 characters in body
Feb
21
revised Is it a bad idea to use a Sieve of Eratosthenes to find all primes up to very large N?
added 1962 characters in body
Feb
21
answered Is it a bad idea to use a Sieve of Eratosthenes to find all primes up to very large N?
Dec
20
comment Consequence of Bertrand's Postulate
It proves that for every $N$ there exist a $k$ such that there are $N$ (or more) pairs of consecutive primes with common difference $k$. The problem if there are $N$ consecutive primes with common difference $k$ is AFAIK open, though is related to Green-Tao theorem.
Dec
19
comment Consequence of Bertrand's Postulate
user19012: It was my fault there was a flaw in the argument. I have corrected it.
Dec
19
revised Consequence of Bertrand's Postulate
Correction of an error in the argument
Dec
15
revised Consequence of Bertrand's Postulate
Clarification of the argument.
Dec
15
answered Consequence of Bertrand's Postulate
Nov
8
awarded  Yearling
Oct
13
answered Solving for $x$ in $x^k \equiv b \pmod n$ where $n$ is not prime and $\gcd(k, \phi(n)) > 1$
Oct
12
answered Algorithm for keeping a concrete version of Euclid's argument simple
Sep
26
comment How many ways can I make six moves on a Rubik's cube?
@Henry: You are right. actually the number I gave allows 18 legal moves while the OP ask for 12 (90 deg twists) so the number of different positions after at most 6 moves is a lot smaller: 1056772. Actually the method given by him (make six random moves until the puzzle is solved) fails for the 96696 positions after 5 moves if it does not take this into account.
Sep
24
comment The number of ones in a binary representation of an integer
@Matt: Why 16x increase? I'm not sure I agree, as you are substituing a few cheap operations with table lookup which needs slow memory access and messes the cache.
Sep
24
answered The number of ones in a binary representation of an integer
Sep
12
comment Bound for divisor function
$\mathrm{Li} x$ is the logarithmic integral $=\int_2^x \frac{ dt}{\log t}$ see here.
Sep
12
answered Bound for divisor function
Jun
21
answered Calculating monodromy
Jun
20
revised Finding the integer $\le n$ with largest number of divisors
added 11 characters in body
Jun
19
awarded  Student