A240987 - OEIS

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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

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OFFSET

1,1

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.

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 *)

PROG

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

CROSSREFS

Cf. A001220, A014127.

Sequence in context: A327317 A215139 A320799 * A338509 A204930 A341102

Adjacent sequences: A240984 A240985 A240986 * A240988 A240989 A240990

KEYWORD

nonn

AUTHOR

Felix Fröhlich, Aug 06 2014

STATUS

approved