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

%I #23 Sep 19 2018 04:06:00

%S 5,4,22,58,57,145,393,401,784,466,715,705,1806,1163,2587,3129,2893,

%T 2991,1677,2416,5988,5769,9298,2672,6210,17879,14628,11879,18314,9833,

%U 9908,12054,9729,10427,34719,15102,27634

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

%C 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.

%H Jens Kruse Andersen, <a href="/A240987/b240987.txt">Table of n, a(n) for n = 1..10000</a>

%H J. B. Dobson, <a href="http://arxiv.org/abs/1103.3907">On Lerch's formula for the Fermat quotient</a>, arXiv:1103.3907 [math.NT], 2011-2014.

%p 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

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

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

%Y Cf. A001220, A014127.

%K nonn

%O 1,1

%A _Felix Fröhlich_, Aug 06 2014