Twice the positions in A051686 at which new primes appear in that sequence.

Terms

a(0) =2a(1) =4a(2) =16a(3) =38a(4) =58a(5) =72a(6) =148a(7) =170a(8) =178a(9) =282a(10) =388a(11) =446a(12) =512a(13) =652a(14) =656a(15) =758a(16) =836a(17) =856a(18) =1514a(19) =1592a(20) =1648a(21) =1712a(22) =1906a(23) =1918a(24) =2034a(25) =2606a(26) =2758a(27) =4094a(28) =4936a(29) =5624