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A051133
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C(2n,n)*n*(2n+1)/2.
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4
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0, 3, 30, 210, 1260, 6930, 36036, 180180, 875160, 4157010, 19399380, 89237148, 405623400, 1825305300, 8143669800, 36064823400, 158685222960, 694247850450, 3022020054900, 13095420237900, 56517076816200, 243023430309660, 1041528987041400
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=(1/2)*A000984(n+1)*A000217(n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 05 2007
a(n)=3*A002802(n-1) - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 02 2007
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MAPLE
| seq(binomial(2*n, n)*binomial(n, (n-2))/2, n=1..23); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 05 2007
with(combinat):a:=n->sum(sum(numbcomp(2*n, n)/2, j=2..n), k=1..n): seq(a(n), n=1..23); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 27 2007
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CROSSREFS
| Equals 1/2 * A000911(n-1).
Sequence in context: A121100 A203366 A130546 * A043030 A178015 A120689
Adjacent sequences: A051130 A051131 A051132 * A051134 A051135 A051136
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KEYWORD
| nonn,easy
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AUTHOR
| Wouter L. J. Meeussen, wouter.meeussen(AT)pandora.be
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