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A235363 (1 + Sum_{k=1..m-1} k^(m-1)) (mod m), for m = 1, 3, 5, 7, 9, ... 2

%I

%S 0,0,0,0,7,0,0,11,0,0,15,0,21,19,0,0,23,1,0,27,0,0,22,0,43,35,0,1,39,

%T 0,0,43,53,0,47,0,0,51,1,0,55,0,69,59,0,79,63,1,0,67,0,0,50,0,0,75,0,

%U 1,79,1,111,83,101,0,87,0,115,91,0,0,95,1,117,99,0,0,103,1,0,107,1,0,78,0,157,115,0,151,119,0,0,123,149,1,127,0,0,131,0,0,135

%N (1 + Sum_{k=1..m-1} k^(m-1)) (mod m), for m = 1, 3, 5, 7, 9, ...

%C a(n) = (1 + Sum_{k=1..2*n} k^(2*n)) (mod 2*n+1), for n = 0, 1, 2, 3, ...

%C The Agoh-Giuga Conjecture is that a(n)=0 iff 2*n+1 is 1 or a prime.

%H MathWorld, <a href="http://mathworld.wolfram.com/GiugasConjecture.html">Giuga's Conjecture</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Agoh-Giuga_conjecture">Agoh-Giuga conjecture</a>

%F a(n) = 0 iff A235364(n) = 0.

%t Table[ Mod[ Sum[ PowerMod[ k, n - 1, n], {k, n - 1}] + 1, n], {n, 1, 201, 2}]

%Y Cf. A007850, A046094, A204187, A228037, A235364.

%K nonn

%O 0,5

%A _Jonathan Sondow_, Jan 07 2014

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Last modified October 18 22:03 EDT 2019. Contains 328211 sequences. (Running on oeis4.)