Strong pseudoprimes to base 21.

Terms

a(0) =221a(1) =703a(2) =793a(3) =3781a(4) =7363a(5) =9061a(6) =11647a(7) =13051a(8) =17767a(9) =19669a(10) =19909a(11) =22681a(12) =27133a(13) =30073a(14) =31021a(15) =38503a(16) =41353a(17) =43213a(18) =58829a(19) =79081a(20) =80137a(21) =83569a(22) =88357a(23) =92509a(24) =96049a(25) =104653a(26) =107213a(27) =121987a(28) =127697a(29) =128627