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

487, 51

Offset: 1

Author

Jonathan Sondow, Jun 16 2010

Keywords

• bref
• hard
• more
• nonn

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.

Examples

			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.

Formula

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

a(1) = A178813(1).