A023539 Convolution of natural numbers with composite numbers.

4, 14, 32, 59, 96, 145, 208, 286, 380, 492, 624, 777, 952, 1151, 1375, 1625, 1902, 2207, 2542, 2909, 3309, 3743, 4212, 4717, 5260, 5842, 6464, 7128, 7836, 8589, 9388, 10235, 11131, 12077, 13074, 14123, 15226, 16384, 17598, 18869, 20198

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Examples

			a(1) = 1*4 = 4;
a(2) = 1*6 + 2*4 = 14;
a(3) = 1*8 + 2*6 + 3*4 = 32;
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002808.

First differences are in A053767.

Programs

PARI

lista(nn) = {my(vc = []); forcomposite(n=2, nn, vc = concat(vc, n); print1(sum(k=1, #vc, (#vc-k+1)*vc[k]), ", "););} \\ Michel Marcus, Feb 11 2018