id:A130519 - OEIS Search Results

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Sum {0<=k<=n, floor(k/4)} (Partial sums of A002265).

+0
3

0, 0, 0, 0, 1, 2, 3, 4, 6, 8, 10, 12, 15, 18, 21, 24, 28, 32, 36, 40, 45, 50, 55, 60, 66, 72, 78, 84, 91, 98, 105, 112, 120, 128, 136, 144, 153, 162, 171, 180, 190, 200, 210, 220, 231, 242, 253, 264, 276, 288, 300, 312, 325, 338, 351, 364, 378, 392, 406, 420, 435, 450 (list; graph; listen)

	OFFSET	`0,6`
	COMMENT	`Complementary with A130482 regarding triangular numbers, in that A130482(n)+4*a(n)=n(n+1)/2=A000217(n).`
	FORMULA	`a(n)=floor(n/4)(n-1-2floor(n/4))=A002265(n)(n-1-2A002265(n)). Also: a(n)=1/2A002265(n)(n-2+A010873(n)). G.f.: g(x)=x^4/((1-x^4)(1-x)^2).`
	CROSSREFS	`Cf. A002264, A002266, A004526, A010872, A010873, A010874, A130481, A130483.` `Sequence in context: A062418 A056168 A019293 this_sequence A001972 A093934 A005705` `Adjacent sequences: A130516 A130517 A130518 this_sequence A130520 A130521 A130522`
	KEYWORD	`nonn`
	AUTHOR	`Hieronymus Fischer (Hieronymus.Fischer(AT)gmx.de), Jun 01 2007`

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

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