A080500 a(n) = (n-1)(n-4)(n-9)...(n-k^2) where k^2 < n <= (k+1)^2.

1, 1, 2, 3, 4, 10, 18, 28, 40, 54, 140, 264, 432, 650, 924, 1260, 1664, 4284, 8100, 13376, 20400, 29484, 40964, 55200, 72576, 93500, 236808, 443232, 728000, 1108380, 1603800, 2235968, 3028992, 4009500, 5206760, 6652800, 8382528, 20867704

Offset: 1

Author

Amarnath Murthy, Mar 19 2003

Keywords

• nonn

Comments

The idea of A080497 to A080500 when applied to Euler's phi function i.e. on phi-torial function defined in A001783 yields A001783 itself for obvious reasons. Is there any other such example?

Examples

			a(6) = (6-1)(6-4)= 10.
		

Crossrefs

Cf. A080497, A080498, A072513.

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003