The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #18 Jul 04 2021 07:54:52
%S 2,37,61,227,1163,2473
%N Numbers k such that 40^k - 39^k is prime.
%C Terms greater than 1000 are often only strong pseudoprimes.
%C No other terms less than 10^5. - _Robert Price_, Jul 24 2012
%o (PARI) is(n)=ispseudoprime(40^n-39^n) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A000043, A057468, A059801, A059802, A062572-A062666.
%K nonn,hard
%O 1,1
%A _Mike Oakes_, May 18 2001, May 19 2001