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Search: id:A007004
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| A007004 |
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(3n)! / ((n+1)(n!)^3).
(Formerly M3125)
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+0
1
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| 1, 3, 30, 420, 6930, 126126, 2450448, 49884120, 1051723530, 22787343150, 504636071940, 11377249621920, 260363981732400, 6034149862347600, 141371511060715200, 3343436236585914480, 79726203788589122490
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Equals A000108*binomial(3*n,n) - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 27 2006
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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FORMULA
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Binomial(2*n,n)*binomial(3*n,n)/(n+1) - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 27 2006
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MAPLE
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[seq(binomial(2*n, n)*binomial(3*n, n)/(n+1), n=0..17)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 27 2006
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MATHEMATICA
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a[n_]:=(3*n)!/((n + 1)*(n!)^3); [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 13 2008]
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CROSSREFS
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Cf. A000108.
Sequence in context: A160473 A144283 A058831 this_sequence A012003 A164945 A064352
Adjacent sequences: A007001 A007002 A007003 this_sequence A007005 A007006 A007007
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jim Propp (propp(AT)math.wisc.edu)
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EXTENSIONS
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More terms from Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 27 2006
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