Bill Dubuque
Reputation
147,435
390/400 score
17 111 407
Impact
~2.7m people reached

# 147,435 Reputation

20 today
 +10 1 hour ago upvote Jacobson radical in $A[x]$ where $A$ is a ring. +10 5 hours ago upvote Simple Proof by induction: “9 divides $n^3 + (n+1)^3 + (n+2)^3$”
115 yesterday
 +35 15:14 3 events An interval with width greater than one contains an integer. +10 22:15 upvote How does one actually show from associativity that one can drop parentheses? +10 17:42 upvote Inverted induction +10 16:42 upvote Checking if something is a unit +10 15:46 upvote Proving $6^n - 1$ is always divisible by $5$ by induction +10 15:03 upvote Is there an elementary proof that $\sum \limits_{k=1}^n \frac1k$ is never an integer? +10 10:22 upvote A prime of the form $38111111\ldots$ +10 04:29 upvote Help understanding this proof - sqrt(2) is irrational +10 03:29 upvote Solve congruence using fermat's theorem
168 2 days ago
 +45 19:32 4 events Prove or disprove : $a^3\mid b^2 \Rightarrow a\mid b$ +40 / -2 10:11 5 events Show that the numbers $(2n + 1)$ and $(4n^2+1)$ are relatively prime +30 21:34 3 events Prove the set $\mathcal{O}_d := \left\{\frac{a + b\sqrt{d}}{2}:a,b \in \mathbb{Z}, a \equiv b \mod 2 \right\}$ is a ring. +25 22:14 2 events Decide if there exist $a$ and $b \in \mathbb{Z}$ such that $a^2=2b^2$. +10 21:29 upvote $x$, $y$, $x+y$ and $x-y$ are prime numbers. What is their sum? +10 13:53 upvote Prove $2015$ divides $1^{2015}+2^{2015}+3^{2015}+\cdots+2015^{2015}$. +10 06:32 upvote Is there an elementary proof that $\sum \limits_{k=1}^n \frac1k$ is never an integer?
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