id:A026029 - OEIS Search Results

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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) = 3. Also T(2n,n), where T is defined in A026022.

+0
2

1, 2, 6, 20, 69, 242, 858, 3068, 11050, 40052, 145996, 534888, 1968685, 7276050, 26993490, 100490220, 375287550, 1405622460, 5278838100, 19873977240, 74994427170, 283595947284, 1074568266756, 4079184055640, 15511924233204, 59083160374952, 225384613313944 (list; graph; listen)

	OFFSET	`0,2`
	FORMULA	`Expansion of (1+x^2C^4)C^2, where C = (1-(1-4x)^(1/2))/(2x) is g.f. for Catalan numbers, A000108.` `a(n)=sum{k=0..n, C(n, k)sum{i=0..k, C(k, 2i)A000108(i+1) }}. - Paul Barry (pbarry(AT)wit.ie), Jul 18 2003`
	CROSSREFS	`Sequence in context: A127152 A082679 A094854 this_sequence A078483 A047036 A045631` `Adjacent sequences: A026026 A026027 A026028 this_sequence A026030 A026031 A026032`
	KEYWORD	`nonn`
	AUTHOR	`Clark Kimberling (ck6(AT)evansville.edu)`

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Last modified July 19 08:04 EDT 2008. Contains 142098 sequences.

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