A117263 - OEIS

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A117263

Row sums of triangle A117262; also, self-convolution of A117264.

1, 2, 7, 64, 1729, 140050, 34032151, 24809438080, 54258241080961, 355988319732185122, 7006918097288599756327, 413751506726794527011353024, 73294838162131470076480154142529 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	FORMULA	`a(n) = Sum_{k=0..n} 3^( n(n-1)/2 - k(k-1)/2 ).`
	PROG	`(PARI) a(n)=sum(k=0, n, 3^((n-k)*(n+k-1)/2))`
	CROSSREFS	`Sequence in context: A181030 A006506 A011821 * A046855 A179043 A116985` `Adjacent sequences: A117260 A117261 A117262 * A117264 A117265 A117266`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Mar 14 2006`

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Last modified February 14 01:35 EST 2012. Contains 205567 sequences.