A178812 (2^(p-1) - 1)/p^2 modulo prime p, if p^2 divides 2^(p-1) - 1.

487, 51

Offset

1,1

Comments

(2^(p-1) - 1)/p^2 modulo p, where p is a Wieferich prime A001220.

(2^(p-1) - 1)/p^2 modulo p, if prime p divides the Fermat quotient (2^(p-1) - 1)/p.

See A001220 for references, links, and additional comments.

Links

Table of n, a(n) for n=1..2.

Formula

a(n) = (2^(p-1) - 1)/p^2 modulo p, where p = A001220(n).

a(1) = A178813(1).

Example

a(1) = 487 as the first Wieferich prime is 1093 and (2^1092 - 1)/1093^2 == 487 (mod 1093).
The 2nd Wieferich prime is 3511 and (2^3510 - 1)/3511^2 == 51 (mod 3511), so a(2) = 51.

Crossrefs

Cf. A001220, A178813.

Sequence in context: A252076 A178813 A178814 * A124667 A142540 A048424

Adjacent sequences: A178809 A178810 A178811 * A178813 A178814 A178815

Keyword

bref,hard,more,nonn

Author

Jonathan Sondow, Jun 16 2010

Status

approved