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A091983 a(0) = 1, a(n) = 20*sigma[3](n). 0
1, 20, 180, 560, 1460, 2520, 5040, 6880, 11700, 15140, 22680, 26640, 40880, 43960, 61920, 70560, 93620, 98280, 136260, 137200, 183960, 192640, 239760, 243360, 327600, 315020, 395640, 408800, 502240, 487800, 635040, 595840, 748980, 745920 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

G.f. A(x) satisfies 0=f(A(x),A(x^2),A(x^4)) where f(u,v,w)=u^2+33v^2+256w^2-18uv+16uw-288vw+220(v-w). - Michael Somos, Jul 19 2004

LINKS

Table of n, a(n) for n=0..33.

FORMULA

a(n) = 20*A001158(n), n>=1. - R. J. Mathar, Mar 23 2019

PROG

(PARI) a(n)=if(n<1, n==0, 20*sigma(n, 3)) /* Michael Somos, Jul 19 2004 */

CROSSREFS

Sequence in context: A140044 A027332 A159538 * A037250 A000144 A219581

Adjacent sequences:  A091980 A091981 A091982 * A091984 A091985 A091986

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, following a suggestion of John McKay, Mar 19 2004

STATUS

approved

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Last modified October 18 10:53 EDT 2021. Contains 348067 sequences. (Running on oeis4.)