Numbers k such that 221*2^k+1 is prime.

Terms

a(0) =1a(1) =7a(2) =9a(3) =13a(4) =21a(5) =67a(6) =77a(7) =81a(8) =89a(9) =101a(10) =117a(11) =131a(12) =161a(13) =181a(14) =229a(15) =641a(16) =753a(17) =789a(18) =911a(19) =1351a(20) =1461a(21) =1819a(22) =2391a(23) =2951a(24) =4381a(25) =4531a(26) =5633a(27) =6577a(28) =6671a(29) =8521