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A115137 Second diagonal of triangle A113647 (called Y(2,1)). +0
2
1, 1, 7, 41, 247, 1545, 9975, 66057, 446455, 3067913, 21372919, 150618121, 1071841271, 7691763721, 55600938999, 404488323081, 2959189475319, 21757613309961, 160691417776119, 1191577871450121, 8868160862158839 (list; graph; listen)
OFFSET

0,3

FORMULA

a(n)= b(n) - 2*b(n-1) with b(n):=A062992(n)= A064062(n+1), n>=1. a(0):=1.

G.f.: (1-2*x)*(2*c(2*x)-1)/(1+x) with c(x) g.f. of A000108 (Catalan).

a(n)= A113647(n, n), n>=1.

EXAMPLE

41=a(3)= A062992(3) - 2*A062992(2) = 67 - 2*13.

CROSSREFS

Sequence in context: A141813 A088165 A108983 this_sequence A036730 A080047 A125120

Adjacent sequences: A115134 A115135 A115136 this_sequence A115138 A115139 A115140

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), Jan 13 2006

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.


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