A188051 Numbers k such that 18^k - 17^k is prime, or a strong pseudoprime.

3, 13, 71, 14533, 26641, 48179

Offset

1,1

Comments

Terms < 10000 found by Mike Oakes.

Term 14533 found by Lelio R Paula in June 2008 corresponding to a probable prime with 18243 digits.

Terms 26641 and 48179 found by Jean-Louis Charton in December 2010 corresponding to probable primes with 33442 and 60478 digits.

a(7) > 10^5. - Robert Price, Nov 30 2012

Links

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

Top probable primes of the form 18^p-17^p

Prog

(PARI) is(n)=ispseudoprime(18^n-17^n) \\ Charles R Greathouse IV, Jun 06 2017

Crossrefs

Cf. A000043, A057468, A059801, A059802, A059803, A062572-A062583, A062585-A062666.

Sequence in context: A307005 A059032 A214812 * A247230 A047159 A086662

Adjacent sequences: A188048 A188049 A188050 * A188052 A188053 A188054

Keyword

nonn,hard

Author

Jean-Louis Charton, Mar 19 2011

Extensions

Edited by M. F. Hasler, Sep 21 2013

Status

approved