A081423 - OEIS

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A081423

Subdiagonal of array of n-gonal numbers A081422.

1, 3, 12, 34, 75, 141, 238, 372, 549, 775, 1056, 1398, 1807, 2289, 2850, 3496, 4233, 5067, 6004, 7050, 8211, 9493, 10902, 12444, 14125, 15951, 17928, 20062, 22359, 24825, 27466, 30288, 33297, 36499, 39900, 43506, 47323, 51357, 55614, 60100 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	COMMENTS	`One of a family of sequences with palindromic generators.`
	FORMULA	`a(n)=(2n^3+n^2+n+2)/2. G.f.: (1-2x+7x^2-6x^3)/(1-x)^5`
	CROSSREFS	`Cf. A081435, A081436, A081437.` `Sequence in context: A183468 A196234 A117655 * A184705 A060298 A073372` `Adjacent sequences: A081420 A081421 A081422 * A081424 A081425 A081426`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), Mar 21 2003`

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Last modified February 17 02:31 EST 2012. Contains 205978 sequences.