id:A084776 - OEIS Search Results

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a(n) = sum of absolute-valued coefficients of (1+2x-x^2)^n.

+0
1

1, 4, 12, 36, 100, 300, 776, 2412, 6304, 19036, 50952, 148896, 393452, 1211444, 3167004, 9672772, 25295248, 76084796, 200590424, 608621376, 1617201648, 4908511140, 12658776540, 38907904188, 102775961200, 310485090044 (list; graph; listen)

	OFFSET	`0,2`
	PROGRAM	`(PARI) for(n=0, 40, S=sum(k=0, 2n, abs(polcoeff((1+2x-x^2)^n, k, x))); print1(S", "))`
	CROSSREFS	`Sequence in context: A002906 A001411 A095350 this_sequence A003212 A156945 A006817` `Adjacent sequences: A084773 A084774 A084775 this_sequence A084777 A084778 A084779`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Jun 14 2003`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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