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Search: id:A000894
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| A000894 |
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(2n)!(2n+1)! /((n+1)! n!^3). |
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+0
4
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| 1, 6, 60, 700, 8820, 116424, 1585584, 22084920, 312869700, 4491418360, 65166397296, 953799087696, 14062422446800, 208618354980000, 3111393751416000, 46619049708716400, 701342468412012900
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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a(n)=A001700*A000984 or a(n)=(A000984 n=0 to)*(A000984 n=1 to)/2. Example: 1,2,6,20,70,252,924,3432,12870... 2,6,20,70,252,924,3432,12870... 1*2/2=1 2*6/2=6 6*20/2=60 20*70/2=700 70*252/2=8 820 etc... - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 23 2007
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REFERENCES
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E. R. Hansen, A Table of Series and Products, Prentice-Hall, Englewood Cliffs, NJ, 1975, p. 96.
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FORMULA
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a(n)=C(2*n+1,n)*C(2*n,n), n>=0 . - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 23 2007
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MAPLE
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seq(binomial(2*n+1, n)*binomial(2*n, n), n=0..16); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 23 2007
seq(binomial(2*n, n)/2*binomial(2*n-2, n-1), n=1..17); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 23 2007
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CROSSREFS
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First differences of A082578. Cf. A002463.
Cf. A001700, A000984.
Adjacent sequences: A000891 A000892 A000893 this_sequence A000895 A000896 A000897
Sequence in context: A106259 A085364 A086984 this_sequence A112117 A065944 A126779
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KEYWORD
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nonn
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AUTHOR
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njas
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