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A026008 T(n,[ n/2 ]), where T = Catalan triangle (A008315). +0
3
1, 1, 2, 3, 5, 9, 14, 28, 42, 90, 132, 297, 429, 1001, 1430, 3432, 4862, 11934, 16796, 41990, 58786, 149226, 208012, 534888, 742900, 1931540, 2674440, 7020405, 9694845, 25662825, 35357670, 94287120, 129644790, 347993910, 477638700, 1289624490, 1767263190 (list; graph; listen)
OFFSET

0,3

COMMENT

a(n) = number of Catalan paths in Quadrant I from (0,0) to (n, GCD(n,2)). - Clark Kimberling (ck6(AT)evansville.edu), Jun 26 2004

FORMULA

a(2n) = C(2n+2, n+1)/(n+2), a(2n+1) = 3C(2n+2, n)/(n+3). - R. Stephan, Apr 30 2004

CROSSREFS

a(2n) = A000108(n+1), a(2n+1) = A000245(n+1).

Sequence in context: A018155 A032089 A105044 this_sequence A101461 A085897 A067798

Adjacent sequences: A026005 A026006 A026007 this_sequence A026009 A026010 A026011

KEYWORD

nonn

AUTHOR

Clark Kimberling (ck6(AT)evansville.edu)

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Last modified December 3 22:15 EST 2009. Contains 170310 sequences.


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