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A235363 (1 + Sum_{k=1..m-1} k^(m-1)) (mod m), for m = 1, 3, 5, 7, 9, ... 2
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, 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, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

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

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

LINKS

Table of n, a(n) for n=0..100.

MathWorld, Giuga's Conjecture

Wikipedia, Agoh-Giuga conjecture

FORMULA

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

MATHEMATICA

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

CROSSREFS

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

Sequence in context: A249119 A154102 A240984 * A211904 A094898 A136115

Adjacent sequences:  A235360 A235361 A235362 * A235364 A235365 A235366

KEYWORD

nonn

AUTHOR

Jonathan Sondow, Jan 07 2014

STATUS

approved

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Last modified July 21 22:02 EDT 2019. Contains 325210 sequences. (Running on oeis4.)