Numbers k such that k^4 + 4 is semiprime.

Terms

a(0) =3a(1) =5a(2) =15a(3) =25a(4) =55a(5) =125a(6) =205a(7) =385a(8) =465a(9) =635a(10) =645a(11) =715a(12) =1095a(13) =1145a(14) =1175a(15) =1245a(16) =1275a(17) =1315a(18) =1375a(19) =1565a(20) =1615a(21) =1675a(22) =1685a(23) =1965a(24) =2055a(25) =2085a(26) =2095a(27) =2405a(28) =2455a(29) =2535