A065223 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 final elements of the rows form a(n).

1, 2, 5, 2, 7, 13, 2, 10, 19, 29, 6, 18, 31, 45, 5, 21, 38, 56, 75, 14, 35, 57, 80, 104, 17, 43, 70, 98, 127, 9, 40, 72, 105, 139, 174, 21, 58, 96, 135, 175, 216, 23, 66, 110, 155, 201, 248, 10, 59, 109, 160, 212, 265, 319, 32, 88, 145, 203, 262, 322, 383, 42, 105