Numbers k such that 4^k + 15 is prime.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =8a(7) =11a(8) =13a(9) =15a(10) =16a(11) =20a(12) =21a(13) =23a(14) =36a(15) =38a(16) =90a(17) =99a(18) =155a(19) =164a(20) =171a(21) =254a(22) =255a(23) =273a(24) =404a(25) =1386a(26) =1941a(27) =1970a(28) =2420a(29) =3759