A130060 Primes p such that p^2 divides 3^p - 2^p - 1; or primes in A127074(n).

2, 3, 7, 179, 619, 17807

Offset

1,1

Comments

The prime p divides 3^p - 2^p - 1. Quotients (3^p - 2^p - 1)/p, where p = Prime[n], are listed in A127071. - Alexander Adamchuk, Jan 31 2008

a(7) > 10^9. [From D. S. McNeil, Mar 16 2009]

Links

Table of n, a(n) for n=1..6.

Mathematica

Do[ n=Prime[k]; f=PowerMod[3, n, n^2] - PowerMod[2, n, n^2] - 1; If[ IntegerQ[ f/n^2 ], Print[n] ], {k, 1, 100000} ]

Crossrefs

Cf. A127071, A127072, A127073, A127074 = numbers n such that n^2 divides 3^n - 2^n - 1. Cf. A130058, A130059, A130061, A130062, A130063.

Sequence in context: A103405 A087311 A053924 * A224894 A266269 A053942

Adjacent sequences: A130057 A130058 A130059 * A130061 A130062 A130063

Keyword

hard,more,nonn

Author

Alexander Adamchuk, May 05 2007

Extensions

2 more terms found by Ryan Propper, Jan 01 2008.

Incorrect a(7), a(8) removed by D. S. McNeil, Mar 16 2009. (The old version was 2,3,7,179,619,17807,135433,1376257.)

Status

approved