A119356 Square pyramidal number (A000330) n(n+1)(2n+1)/6 is squarefree.

1, 2, 3, 4, 5, 6, 9, 10, 11, 14, 17, 18, 19, 20, 21, 22, 28, 29, 30, 33, 34, 35, 36, 38, 41, 42, 43, 44, 45, 46, 51, 52, 57, 58, 59, 61, 65, 66, 68, 69, 70, 76, 77, 78, 82, 83, 85, 86, 89, 90, 91, 92, 93, 101, 102, 105, 106, 109, 110, 113, 114, 115, 116, 117, 118, 123, 126