17 What is the algebraic intuition behind Vieta jumping in IMO1988 Problem 6? 6 Exterior Derivative vs. Covariant Derivative vs. Lie Derivative 5 Prove that there is no function $f:\mathbb{Z}_{\ge 0}\rightarrow \mathbb{Z}_{\ge 0}$ such that $f(f(n-1))=f(n+1)-f(n)$ 5 What is the algebraic intuition behind Vieta jumping in IMO1988 Problem 6? 3 Contracting the metric tensor with itself using Einstein summation

### Reputation (1,554)

 +5 Proof nilradical is intersection of prime ideals. +10 Awkward Functional Equation $f(f(x))=(x+1)f(x)$ +10 Spivak's calculus, chapter 2 question 3 (d) +10 Exterior Derivative vs. Covariant Derivative vs. Lie Derivative

### Questions (4)

 32 Math olympiad 1988 problem 6: canonical solution (2) without Vieta jumping 6 Is there a formula for calculating the sum of all products of $p$ different integers $\le n$? 1 Proof nilradical is intersection of prime ideals. 1 $(2a)^2 +b^2=c^{4}a^2d^2 +4d$ integer solutions

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 34 elementary-number-theory × 9 16 functional-equations × 10 31 contest-math × 5 8 differential-geometry × 2 25 square-numbers × 5 7 ordinary-differential-equations × 5 22 infinite-descent × 2 7 calculus × 3 22 induction × 2 6 tensors × 5

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