Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.

Terms

a(0) =4a(1) =6a(2) =180a(3) =3390a(4) =18060a(5) =19380a(6) =34500a(7) =92220a(8) =92640a(9) =96180a(10) =114660a(11) =127680a(12) =133980a(13) =140760a(14) =159630a(15) =161880a(16) =172170a(17) =207480a(18) =254280a(19) =255840a(20) =263820a(21) =296910a(22) =309780a(23) =378570a(24) =380880a(25) =397590a(26) =408690a(27) =422880a(28) =432660a(29) =440550