A161569 Sum of first n nonprimes minus their indices.

0, 2, 5, 9, 13, 17, 22, 28, 34, 40, 47, 55, 63, 71, 80, 89, 98, 107, 116, 126, 137, 148, 159, 170, 181, 193, 205, 217, 230, 244, 258, 272, 287, 302, 317, 332, 347, 363, 379, 395, 411, 427, 444, 462, 480, 498, 516, 534, 553, 572, 591, 611, 632, 653, 674, 695, 716

Offset: 1

Author

Juri-Stepan Gerasimov, Jun 14 2009

Keywords

• nonn
• easy

Comments

The sum of first n nonprimes is in A051349.

Partial sums of A073425. - Jaroslav Krizek, Jun 27 2009

Examples

			a(1) = 1-1 = 0; a(2) = 0+4-2 = 2, a(3) = 2+6-3 = 5; a(4) = 5+8-4 = 9.
		

Crossrefs

Cf. A073425, A051349, A018252, A112997.

Formula

a(n) = A051349(n)-n*(n+1)/2.

a(n) = a(n-1)+A018252(n)-n, a(1) = 0. - Klaus Brockhaus, Dec 16 2010

Extensions

a(54)-a(57) from Stefano Spezia, May 26 2025