Indices of prime Jacobsthal numbers.

Terms

a(0) =3a(1) =4a(2) =5a(3) =7a(4) =11a(5) =13a(6) =17a(7) =19a(8) =23a(9) =31a(10) =43a(11) =61a(12) =79a(13) =101a(14) =127a(15) =167a(16) =191a(17) =199a(18) =313a(19) =347a(20) =701a(21) =1709a(22) =2617a(23) =3539a(24) =5807a(25) =10501a(26) =10691a(27) =11279a(28) =12391a(29) =14479