A033465 First differences of sequence {1/(n^2+1)} (numerators).

1, 3, 1, 7, 9, 11, 13, 3, 17, 19, 21, 23, 1, 27, 29, 31, 33, 7, 37, 39, 41, 43, 9, 47, 49, 51, 53, 11, 57, 59, 61, 63, 13, 67, 69, 71, 73, 3, 77, 79, 81, 83, 17, 87, 89, 91, 93, 19, 97, 99, 101, 103, 21, 107, 109, 111, 113