A024513 a(n) = position of n^2 + (n+1)^2 in A004431 (sums of 2 distinct nonzero squares).

1, 3, 6, 12, 18, 25, 34, 42, 55, 66, 80, 94, 110, 127, 144, 162, 183, 204, 224, 248, 272, 296, 322, 348, 378, 407, 434, 469, 500, 533, 565, 601, 636, 674, 712, 752, 792, 832, 873, 918, 960, 1007, 1051, 1094, 1144, 1191, 1240, 1290, 1342, 1395, 1448, 1504