id:A126950 - OEIS Search Results

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a(1) = 1; for n>1, a(n) = the smallest number p > a(n-1) such that (a(n-1)+p)/2 is a cube.

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1, 15, 39, 89, 161, 271, 415, 609, 849, 1151, 1511, 1945, 2449, 3039, 3711, 4481, 5345, 6319, 7399, 8601, 9921, 11375, 12959, 14689, 16561, 18591, 20775, 23129, 25649, 28351, 31231, 34305, 37569, 41039, 44711, 48601, 52705, 57039, 61599, 66401 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n) = ((2n +1)(2n^2 + 2n -1)+ 5(-1)^n)/4; a(n) = a(n-1)+2n^3; G.f. = (1 - 2x + 14x^2 - 2x^3 + x^4)/((1 + x)(1 - x)^4).`
	MATHEMATICA	`Table[((2n +1)(2n^2 + 2n -1)+ 5*(-1)^n)/4, {n, 83}]`
	CROSSREFS	`Cf. A081352, A126938.` `Sequence in context: A121051 A139042 A020142 this_sequence A091847 A062222 A044092` `Adjacent sequences: A126947 A126948 A126949 this_sequence A126951 A126952 A126953`
	KEYWORD	`nonn`
	AUTHOR	`Zak Seidov (zakseidov(AT)gmail.com), Mar 18 2007`

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Last modified July 23 17:35 EDT 2008. Contains 142285 sequences.

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