a(n) = position of 1 + n^2 in A000404 (sums of 2 nonzero squares).

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =10a(5) =14a(6) =18a(7) =23a(8) =29a(9) =36a(10) =43a(11) =49a(12) =59a(13) =67a(14) =76a(15) =86a(16) =97a(17) =108a(18) =119a(19) =132a(20) =143a(21) =157a(22) =169a(23) =182a(24) =198a(25) =215a(26) =230a(27) =245a(28) =263a(29) =280