A065227 Fill a triangular array by rows by writing numbers 1 up to b(0), 1 up to b(1), etc., where b(n) are the triangular numbers. The first elements of the rows form a(n).
1, 1, 3, 3, 1, 6, 2, 9, 2, 11, 21, 11, 23, 8, 22, 1, 17, 34, 7, 26, 46, 12, 34, 57, 15, 40, 66, 15, 43, 72, 11, 42, 74, 2, 36, 71, 107, 24, 62, 101, 5, 46, 88, 131, 22, 67, 113, 160, 37, 86, 136, 187, 49, 102, 156, 1, 57, 114, 172, 231, 60, 121, 183, 246, 57, 122, 188, 255
Offset: 0