Positions of even numbers in A000404 (sums of 2 nonzero squares).

Terms

a(0) =1a(1) =3a(2) =4a(3) =7a(4) =8a(5) =10a(6) =12a(7) =13a(8) =15a(9) =18a(10) =19a(11) =21a(12) =24a(13) =25a(14) =27a(15) =28a(16) =29a(17) =32a(18) =34a(19) =35a(20) =37a(21) =38a(22) =41a(23) =43a(24) =45a(25) =46a(26) =47a(27) =50a(28) =51a(29) =55