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A023539 Convolution of natural numbers with composite numbers. 1
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

Table of n, a(n) for n=1..41.

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

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Last modified September 19 18:47 EDT 2018. Contains 315210 sequences. (Running on oeis4.)