A111715 Sum of the squares of the first n squarefree numbers.

0, 1, 5, 14, 39, 75, 124, 224, 345, 514, 710, 935, 1224, 1585, 2026, 2510, 3039, 3715, 4556, 5456, 6417, 7506, 8662, 9887, 11256, 12700, 14221, 15902, 17666, 19515, 21631, 23840, 26441, 29250, 32275, 35524, 38888, 42369, 46090, 49934, 54159

Offset: 0

Author

Jonathan Vos Post, Nov 17 2005

Keywords

• nonn

Examples

			a(10) = 1^2 + 2^2 + 3^2 + 5^2 + 6^2 + 7^2 + 10^2 + 11^2 + 13^2 + 14^2 = 710.
		

Links

• Eric Weisstein's World of Mathematics, Squarefree.

Crossrefs

Cf. A005117.

Programs

Mathematica

Join[{0},Accumulate[Select[Range[100],SquareFreeQ]^2]] (* Harvey P. Dale, Apr 08 2015 *)

Formula

a(n) = Sum_{k=1..n} A005117(k)^2.

a(n) ~ c * n^3, where c = Pi^4/108 = 0.901936... . - Amiram Eldar, Jan 19 2024