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A078128 Number of ways to write n as sum of cubes>1. +0
7
0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 2, 0, 0, 1, 0, 0, 1, 0, 2, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 1, 0, 0, 1, 0, 2, 1, 0, 2, 0, 0, 1, 0, 2, 1, 0, 2, 0, 0, 1, 0, 2, 1 (list; graph; listen)
OFFSET

1,64

COMMENT

a(A078129(n))=0; a(A078130(n))=1; a(A078131(n))>0;

Conjecture (lower bound): for all k exists b(k) such that a(n)>k for n>b(k); see b(0)=A078129(83)=154 and b(1)=A078130(63)=218.

LINKS

Index entries for sequences related to sums of cubes

Eric Weisstein's World of Mathematics, Cubic Number.

FORMULA

a(n) = 1/n*Sum_{k=1..n} (b(k)-1)*a(n-k), a(0) = 1, where b(k) is sum of cube divisors of k. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Nov 20 2002

EXAMPLE

a(160)=4: 160 = 20*2^3 = 4^3+12*2^3 = 2*4^3+4*2^3 = 5^3+3^3+2^3.

CROSSREFS

Cf. A000578, A003108, A001235, A078132, A078133, A078134.

Adjacent sequences: A078125 A078126 A078127 this_sequence A078129 A078130 A078131

Sequence in context: A016232 A007949 A078595 this_sequence A112607 A091970 A093955

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 19 2002

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Last modified October 15 09:18 EDT 2008. Contains 145015 sequences.


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