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A277167 Prime numbers p such that (-1)^h + (h!)^2 == 0 (mod p^2) where h = (p-1)/2. 0
3, 11, 31, 47, 53 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The above congruence is true modulo p for all odd primes. See A089043. But like for Wilson congruence, it is true modulo p^2, for a restricted number of primes. After 53, the next one (if any) seems very far away (>500000).

The fact that the congruence is true modulo p for all odd primes was proved by Lagrange in 1771. Using a theorem of Mathews (1892) and Eisenstein's logarithmetic rule for the Fermat quotient, the condition stated in the definition can be restated as W_p == -2q_p(2) (mod p), where W_p is the Wilson quotient of p (A007619) and q_p(2) is the Fermat quotient of p, base 2 (A007663). - John Blythe Dobson, Jul 31 2017

REFERENCES

Lagrange, "Démonstration d’un théoreme nouveau concernant les nombres premiers," Nouveaux Mémoires de l’Académie Royale des Sciences et Belles-Lettres [de Berlin], année 1771 (published 1783), 125-137.

G. B. Mathews, Theory of Numbers, part 1 [all published] (Cambridge, 1892), 318.

LINKS

Table of n, a(n) for n=1..5.

René Gy, Find the next "Wilson-like" prime.

EXAMPLE

(-1)^((11-1)/2)+(((11-1)/2)!)^2 = 14399 = 7*11^2*17.

PROG

(PARI) lista(nn) = forprime(p=3, nn, if ((((-1)^((p-1)/2)+(((p-1)/2)!)^2) % p^2) == 0, print1(p, ", "))); \\ Michel Marcus, Oct 02 2016

CROSSREFS

Cf. A007540, A089043.

Sequence in context: A119215 A266970 A057172 * A277049 A261148 A071568

Adjacent sequences:  A277164 A277165 A277166 * A277168 A277169 A277170

KEYWORD

nonn,hard,more

AUTHOR

René Gy, Oct 01 2016

STATUS

approved

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Last modified October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)