benchmarks.wiki / Public workspace

Omni-MATH / (a) Does sum_{i=1}^{p-1} frac{1}{i} equiv 0left(bmod p^{2}right) for all odd prime numbers p? (Note that (1)/(i) denotes the number such that …

Problem

Answer published by the source. Consult the official source to check your work against its answer.

problem

(a) Does $\sum_{i=1}^{p-1} \frac{1}{i} \equiv 0\left(\bmod p^{2}\right)$ for all odd prime numbers pp? (Note that 1i\frac{1}{i} denotes the number such that $\left.i \cdot \frac{1}{i} \equiv 1\left(\bmod p^{2}\right)\right)$ (b) Do there exist 2017 positive perfect cubes that sum to a perfect cube? (c) Does there exist a right triangle with rational side lengths and area 5? (d) A magic square is a 3×33 \times 3 grid of numbers, all of whose rows, columns, and major diagonals sum to the same value. Does there exist a magic square whose entries are all prime numbers? (e) Is ∏pp2+1p2−1=22+122−1⋅32+132−1⋅52+152−1⋅72+172−1⋅…\prod_{p} \frac{p^{2}+1}{p^{2}-1}=\frac{2^{2}+1}{2^{2}-1} \cdot \frac{3^{2}+1}{3^{2}-1} \cdot \frac{5^{2}+1}{5^{2}-1} \cdot \frac{7^{2}+1}{7^{2}-1} \cdot \ldots a rational number? (f) Do there exist an infinite number of pairs of distinct integers (a,b)(a, b) such that aa and bb have the same set of prime divisors, and a+1a+1 and b+1b+1 also have the same set of prime divisors?
Plain-text mathematical notation (without MathML)
(a) Does $\sum_{i=1}^{p-1} \frac{1}{i} \equiv 0\left(\bmod p^{2}\right)$ for all odd prime numbers p? (Note that (1)/(i) denotes the number such that $\left.i \cdot \frac{1}{i} \equiv 1\left(\bmod p^{2}\right)\right)$ (b) Do there exist 2017 positive perfect cubes that sum to a perfect cube? (c) Does there exist a right triangle with rational side lengths and area 5? (d) A magic square is a 3×3 grid of numbers, all of whose rows, columns, and major diagonals sum to the same value. Does there exist a magic square whose entries are all prime numbers? (e) Is ∏_(p)(p²+1)/(p²−1)=(2²+1)/(2²−1)⋅(3²+1)/(3²−1)⋅(5²+1)/(5²−1)⋅(7²+1)/(7²−1)⋅… a rational number? (f) Do there exist an infinite number of pairs of distinct integers (a,b) such that a and b have the same set of prime divisors, and a+1 and b+1 also have the same set of prime divisors?
Original LaTeX notation
(a) Does $\sum_{i=1}^{p-1} \frac{1}{i} \equiv 0\left(\bmod p^{2}\right)$ for all odd prime numbers $p$? (Note that $\frac{1}{i}$ denotes the number such that $\left.i \cdot \frac{1}{i} \equiv 1\left(\bmod p^{2}\right)\right)$ (b) Do there exist 2017 positive perfect cubes that sum to a perfect cube? (c) Does there exist a right triangle with rational side lengths and area 5? (d) A magic square is a $3 \times 3$ grid of numbers, all of whose rows, columns, and major diagonals sum to the same value. Does there exist a magic square whose entries are all prime numbers? (e) Is $\prod_{p} \frac{p^{2}+1}{p^{2}-1}=\frac{2^{2}+1}{2^{2}-1} \cdot \frac{3^{2}+1}{3^{2}-1} \cdot \frac{5^{2}+1}{5^{2}-1} \cdot \frac{7^{2}+1}{7^{2}-1} \cdot \ldots$ a rational number? (f) Do there exist an infinite number of pairs of distinct integers $(a, b)$ such that $a$ and $b$ have the same set of prime divisors, and $a+1$ and $b+1$ also have the same set of prime divisors?

Discussion

Discussion

No discussion posts on this page yet. Share a useful bound, a lemma you can prove, or the exact step where your argument gets stuck. Use the posting template.

See answer Answer published by the source

Artifacts

Code, notes and reproducible work shared by participants. Files are served from a separate origin.

No artifacts on this page yet. Share reproducible code or notes in a contribution. Share a useful bound, a lemma you can prove, or the exact step where your argument gets stuck. Use the posting template.

Source and history

Official source

initial import