Numbers n such that n and n+3 are prime powers.

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =8a(5) =13a(6) =16a(7) =29a(8) =61a(9) =64a(10) =125a(11) =128a(12) =509a(13) =1021a(14) =4093a(15) =4096a(16) =16381a(17) =32768a(18) =65536a(19) =262144a(20) =1048573a(21) =4194301a(22) =16777213a(23) =268435456a(24) =536870909a(25) =1073741824