id:A099513 - OEIS Search Results

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Row sums of triangle A099512, so that a(n) = Sum_{k=0..n} coefficient of z^k in (1 + 3*z + z^2)^(n-[k/2]), where [k/2] is the integer floor of k/2.

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1, 4, 8, 27, 89, 257, 784, 2421, 7336, 22324, 68147, 207549, 632177, 1926608, 5870089, 17884476, 54493120, 166034731, 505883825, 1541369745, 4696373312, 14309268413, 43598614528, 132839740908, 404746601923, 1233213978037 (list; graph; listen)

	OFFSET	`0,2`
	FORMULA	`G.f.: (1+2x-x^2)/(1-2x-x^2-7*x^3+x^4).`
	PROGRAM	`(PARI) a(n)=sum(k=0, n, polcoeff((1+3x+x^2+xO(x^k))^(n-k\2), k))`
	CROSSREFS	`Cf. A099512.` `Adjacent sequences: A099510 A099511 A099512 this_sequence A099514 A099515 A099516` `Sequence in context: A026085 A036720 A110132 this_sequence A104042 A117864 A020138`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Oct 21 2004`

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Last modified November 8 20:39 EST 2009. Contains 166234 sequences.

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