id:A026030 - OEIS Search Results

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a(n) = number of (s(0), s(1), ..., s(2n)) such that s(i) is a nonnegative integer and |s(i) - s(i-1)| = 1 for i = 1,2,...,n, s(0) = 3, s(2n) = 5. Also a(n) = T(2n,n-1), where T is defined in A026022.

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1, 4, 15, 56, 209, 780, 2912, 10880, 40698, 152456, 572033, 2150040, 8095425, 30535260, 115377660, 436698240, 1655607390, 6286707000, 23908446510, 91057063344, 347281885818, 1326262602104, 5071418015120, 19415851639296, 74419447792340 (list; graph; listen)

	OFFSET	`2,2`
	FORMULA	`C(2n, n-1) - C(2n, n-5). G.f.: (1+x^2C^4)*C^4, where C=(1-sqrt(1-4x))/(2x). - Ralf Stephan, Jan 09 2005`
	CROSSREFS	`Sequence in context: A001353 A106707 A125905 this_sequence A047038 A158500 A001791` `Adjacent sequences: A026027 A026028 A026029 this_sequence A026031 A026032 A026033`
	KEYWORD	`nonn`
	AUTHOR	`Clark Kimberling (ck6(AT)evansville.edu)`

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Last modified November 29 12:46 EST 2009. Contains 167659 sequences.

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