A178813 (Prime(n)^(p-1) - 1)/p^2 mod p, where p is the first prime that divides (prime(n)^(p-1) - 1)/p.

487, 4, 1, 1, 46, 1, 0, 1, 11, 1, 2, 1, 0, 2

Offset

1,1

Comments

(Prime(n)^(p-1) - 1)/p^2 mod p, where p = A174422(n) is the first Wieferich prime base prime(n).

(Prime(n)^(p-1) - 1)/p^2 mod p, where p is the first prime such that p^2 divides prime(n)^(p-1) - 1.

See references and additional comments, links, and cross-refs in A001220 and A039951.

Links

Table of n, a(n) for n=1..14.

Wikipedia, Generalized Wieferich primes

Formula

a(n) = k mod 2, if prime(n) = 4k+1.

a(n) = A178814(prime(n)) .

a(1) = A178812(1).

Example

Prime(2) = 3 and the first prime p that divides (3^(p-1) - 1)/p is 11, so a(2) = (3^10 - 1)/11^2 mod 11 = 488 mod 11 = 4.

Crossrefs

Cf. A001220, A039951, A174422, A178812, A178814.

Sequence in context: A097765 A179428 A252076 * A178814 A178812 A124667

Adjacent sequences: A178810 A178811 A178812 * A178814 A178815 A178816

Keyword

hard,more,nonn

Author

Jonathan Sondow, Jun 17 2010

Status

approved