id:A081441 - OEIS Search Results

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a(n)=(2n^3-n^2-n+2)/2. G.f.: (1-4x+11x^2-8x^3)/(1-x)^5.

+0
3

1, 1, 6, 22, 55, 111, 196, 316, 477, 685, 946, 1266, 1651, 2107, 2640, 3256, 3961, 4761, 5662, 6670, 7791, 9031, 10396, 11892, 13525, 15301, 17226, 19306, 21547, 23955, 26536, 29296, 32241, 35377, 38710, 42246, 45991, 49951, 54132, 58540, 63181 (list; graph; listen)

	OFFSET	`0,3`
	COMMENT	`Diagonal in array of n-gonal numbers A081422.`
	FORMULA	`sum (((n+j-1)^2-j^2+1)/2,j=0..n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 13 2006`
	CROSSREFS	`Cf. A081436, A081437, A081438.` `Adjacent sequences: A081438 A081439 A081440 this_sequence A081442 A081443 A081444` `Sequence in context: A072972 A092185 A034134 this_sequence A127760 A066188 A071239`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 21 2003`

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Last modified October 11 13:47 EDT 2008. Contains 144830 sequences.

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