id:A099511 - OEIS Search Results

Search: id:A099511

Displaying 1-1 of 1 results found.

page 1

Row sums of triangle A099510, so that a(n) = Sum_{k=0..n} coefficient of z^k in (1 + 2*z + z^2)^(n-[k/2]), where [k/2] is the integer floor of k/2.

+0
2

1, 3, 6, 17, 45, 116, 305, 799, 2090, 5473, 14329, 37512, 98209, 257115, 673134, 1762289, 4613733, 12078908, 31622993, 82790071, 216747218, 567451585, 1485607537, 3889371024, 10182505537, 26658145587, 69791931222, 182717648081 (list; graph; listen)

	OFFSET	`0,2`
	FORMULA	`G.f.: (1+x-x^2)/(1-2x-x^2-2x^3+x^4). a(n) = Sum_{k=0..n} binomial(2n-2[k/2], k).`
	PROGRAM	`(PARI) a(n)=sum(k=0, n, polcoeff((1+2x+x^2+xO(x^k))^(n-k\2), k))`
	CROSSREFS	`Cf. A099510.` `Sequence in context: A129905 A143363 A006081 this_sequence A143093 A117712 A106158` `Adjacent sequences: A099508 A099509 A099510 this_sequence A099512 A099513 A099514`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Oct 21 2004`

page 1

Search completed in 0.002 seconds

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

AT&T Labs Research