Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #19 May 07 2024 05:32:25
%S 2,3,101,1117,3109,44959,55259
%N Numbers k such that 91^k - 90^k is prime.
%C Terms greater than 1000 are often only strong pseudoprimes.
%C a(8) > 10^5. - _Robert Price_, Jul 21 2015
%t Select[Range[0, 100000], PrimeQ[91^# - 90^#] &] (* _Robert Price_, Jul 21 2015 *)
%o (PARI) is(n)=ispseudoprime(91^n-90^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)-a(7) from _Robert Price_, Jul 21 2015