A240987 (2^(p-1) modulo p^2) + (3^(p-1) modulo p^2), where p = prime(n).

5, 4, 22, 58, 57, 145, 393, 401, 784, 466, 715, 705, 1806, 1163, 2587, 3129, 2893, 2991, 1677, 2416, 5988, 5769, 9298, 2672, 6210, 17879, 14628, 11879, 18314, 9833, 9908, 12054, 9729, 10427, 34719, 15102, 27634

Offset: 1

Author

Felix Fröhlich, Aug 06 2014

Keywords

• nonn

Comments

A value of 2 would indicate a prime that is Wieferich to bases 2 and 3 (i.e., a term of both A001220 and A014127). No such prime is currently known.

Links

• Jens Kruse Andersen, Table of n, a(n) for n = 1..10000
• J. B. Dobson, On Lerch's formula for the Fermat quotient, arXiv:1103.3907 [math.NT], 2011-2014.

Crossrefs

Cf. A001220, A014127.

Programs

Maple

map(p -> (2 &^ (p-1) mod p^2) + (3 &^ (p-1) mod p^2), select(isprime,[2,seq(2*i+1,i=1..1000)])); # Robert Israel, Aug 11 2014

Mathematica

Table[p = Prime[n]; PowerMod[2, p-1, p^2] + PowerMod[3, p-1, p^2], {n, 40}] (* Jean-François Alcover, Sep 19 2018 *)

PARI

forprime(p=2, 1e2, a=2^(p-1)%p^2; b=3^(p-1)%p^2; print1(a+b, ", "))