A078128 - OEIS

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A078128

Number of ways to write n as sum of cubes>1.

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; refs; listen; history; internal format)

	OFFSET	`1,64`
	COMMENTS	`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/nSum_{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.rs), Nov 20 2002`
	EXAMPLE	`a(160)=4: 160 = 202^3 = 4^3+122^3 = 24^3+42^3 = 5^3+3^3+2^3.`
	CROSSREFS	`Cf. A000578, A003108, A001235, A078132, A078133, A078134.` `Sequence in context: A007949 A191265 A078595 * A191269 A112607 A161371` `Adjacent sequences: A078125 A078126 A078127 * A078129 A078130 A078131`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 19 2002`

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Last modified February 15 11:03 EST 2012. Contains 205763 sequences.