A065231 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 heptagonal numbers (A000566). The first elements of the rows form a(n).

1, 1, 3, 6, 3, 8, 14, 3, 11, 20, 30, 7, 19, 32, 46, 6, 22, 39, 57, 76, 15, 36, 58, 81, 105, 18, 44, 71, 99, 128, 10, 41, 73, 106, 140, 175, 22, 59, 97, 136, 176, 217, 24, 67, 111, 156, 202, 249, 11, 60, 110, 161, 213, 266, 320, 33, 89, 146, 204, 263, 323, 384, 43, 106