A023539 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

EXAMPLE

a(1) = 1*4 = 4;

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

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

PROG

(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

CROSSREFS

Cf. A002808.

First differences are in A053767.

Sequence in context: A072475 A001740 A129395 * A159920 A036486 A023627

Adjacent sequences: A023536 A023537 A023538 * A023540 A023541 A023542

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved