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A260507
Primes p such that (2^p+1)^(p-1) == 1 (mod p^2).
2
2, 7, 179, 619, 17807
OFFSET
1,1
COMMENTS
A000040(n) such that A260531(n) = 1.
Is this a subsequence of A130060?
a(6) > 10325801 if it exists.
a(6) > 3037000499 if it exists. - Hiroaki Yamanouchi, Aug 20 2015
EXAMPLE
2^7 + 1 = 129 and 129^6 == 1 (mod 7^2), so 7 is a term of the sequence.
MATHEMATICA
Select[Prime@ Range@ 120, Mod[(2^# + 1)^(# - 1), #^2] == 1 &] (* Michael De Vlieger, Jul 29 2015 *)
PROG
(PARI) forprime(p=2, , if(Mod(2^p+1, p^2)^(p-1)==1, print1(p, ", ")))
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Felix Fröhlich, Jul 27 2015
STATUS
approved