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A051789 C(n)*(C(n)-1)/2, where C(n) are the Catalan numbers (A000108). 2
0, 0, 1, 10, 91, 861, 8646, 91806, 1021735, 11817091, 141044410, 1727867505, 21634392066, 275949833550, 3576313319580, 46995004939590, 625082396235615, 8403885722249655, 114069363630025650, 1561609590480856455, 21543838440848427990 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

FORMULA

a(n) = binomial(binomial(2*n,n)/(n+1),2). - Zerinvary Lajos, May 29 2006

MAPLE

[seq (binomial(binomial(2*n, n)/(n+1), 2), n=0..24)]; # Zerinvary Lajos, May 29 2006

MATHEMATICA

(#(#-1))/2&/@CatalanNumber[Range[0, 20]] (* Harvey P. Dale, Aug 08 2014 *)

PROG

(MAGMA) [Catalan(n)*(Catalan(n)-1)/2: n in [0..20]] // Vincenzo Librandi, Aug 09 2014

CROSSREFS

Cf. A000108.

Sequence in context: A096261 A015455 A110410 * A267833 A015467 A144783

Adjacent sequences:  A051786 A051787 A051788 * A051790 A051791 A051792

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 10 1999

STATUS

approved

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Last modified April 2 19:30 EDT 2020. Contains 333190 sequences. (Running on oeis4.)