|
%I #16 Jul 04 2021 08:54:36
%S 47,139,227,2339,4919,21319
%N Numbers k such that 71^k - 70^k is prime.
%C Terms greater than 1000 are often only strong pseudoprimes.
%C a(7) > 10^5. - _Robert Price_, Feb 17 2014
%o (PARI) is(n)=ispseudoprime(71^n-70^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
%E a(6) from _Robert Price_, Feb 17 2014
| 