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A260531
a(n) = (2^p+1)^(p-1) modulo p^2, where p is prime(n).
2
1, 0, 21, 1, 45, 79, 120, 305, 484, 697, 404, 186, 1354, 603, 612, 2757, 945, 3051, 3552, 498, 950, 1186, 2657, 1781, 6403, 9192, 8035, 1927, 2181, 2713, 6097, 2621, 10139, 3476, 10878, 8608, 22609, 21028, 24550, 19031, 1, 12852, 33426, 27793, 34279, 11543
OFFSET
1,3
COMMENTS
The primes where a(n) == 1 are given by A260507.
LINKS
FORMULA
a(n) = A098640(n)^(A000040(n)-1) modulo A000040(n)^2.
MATHEMATICA
f[n_] := Block[{p = Prime@ n}, PowerMod[2^p + 1, p - 1, p^2]]; Array[f, 46] (* Robert G. Wilson v, Jul 29 2015 *)
PROG
(PARI) a(n) = lift(Mod(2^prime(n)+1, prime(n)^2)^(prime(n)-1))
CROSSREFS
KEYWORD
nonn
AUTHOR
Felix Fröhlich, Jul 28 2015
STATUS
approved