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 A260507 Primes p such that (2^p+1)^(p-1) == 1 (mod p^2). 2
 2, 7, 179, 619, 17807 (list; graph; refs; listen; history; text; internal format)
 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 LINKS 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 Cf. A098640, A127074, A130060, A130062, A260531. Sequence in context: A159034 A336249 A120381 * A173240 A042359 A015174 Adjacent sequences:  A260504 A260505 A260506 * A260508 A260509 A260510 KEYWORD nonn,hard,more AUTHOR Felix FrÃ¶hlich, Jul 27 2015 STATUS approved

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Last modified May 6 03:40 EDT 2021. Contains 343580 sequences. (Running on oeis4.)