Primes p+2^n arising in A056206.

Terms

a(0) =3a(1) =5a(2) =7a(3) =11a(4) =19a(5) =37a(6) =67a(7) =131a(8) =263a(9) =523a(10) =1031a(11) =2053a(12) =4099a(13) =8209a(14) =16421a(15) =32771a(16) =65539a(17) =131101a(18) =262147a(19) =524341a(20) =1048583a(21) =2097169a(22) =4194371a(23) =8388619a(24) =16777259a(25) =33554473a(26) =67108961a(27) =134217757a(28) =268435459a(29) =536870923