Numbers k such that k![4] - 256 is prime, where k![4] = A007662(k) = quadruple factorial.

Terms

a(0) =15a(1) =17a(2) =19a(3) =21a(4) =23a(5) =25a(6) =33a(7) =39a(8) =41a(9) =43a(10) =53a(11) =63a(12) =67a(13) =73a(14) =157a(15) =167a(16) =181a(17) =195a(18) =221a(19) =327a(20) =363a(21) =419a(22) =849a(23) =861a(24) =1233a(25) =1265a(26) =1599a(27) =2413a(28) =2515a(29) =4009