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A051577
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(2*n+3)!!/3, related to A001147 (odd double factorials).
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12
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1, 5, 35, 315, 3465, 45045, 675675, 11486475, 218243025, 4583103525, 105411381075, 2635284526875, 71152682225625, 2063427784543125, 63966261320836875, 2110886623587616875, 73881031825566590625
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Row m=3 of the array A(3; m,n) := (2*n+m)!!/m!!, m >= 0, n >= 0.
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LINKS
| Guo-Niu Han, Enumeration of Standard Puzzles
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FORMULA
| a(n) = (2*n+3)!!/3!!; e.g.f.: 1/(1-2*x)^(5/2).
a(n) ~ 4/3*sqrt(2)*n^2*2^n*e^-n*n^n*{1 + 47/24*n^-1 + ...}. - Joe Keane (jgk(AT)jgk.org), Nov 23 2001
Ramanujan polynomials -psi_n(n, x) evaluated at 0. - Ralf Stephan, Apr 16 2004
a(n)=(2^(2+n)*Gamma(n+5/2))/(3*sqrt(pi)) [From G. W. Barbosa (gwbarbosa(AT)yahoo.com), May 05 2010]
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MAPLE
| with(finance):seq(mul(cashflows([k, k, 1], 0), k=2..n), n=1..22); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 22 2008]
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CROSSREFS
| Cf. A000165, A001147(n+1), A002866(n+1) (m=0..2 rows).
Sequence in context: A015683 A000357 * A102147 A124564 A113342 A201367
Adjacent sequences: A051574 A051575 A051576 * A051578 A051579 A051580
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KEYWORD
| easy,nonn
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AUTHOR
| Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de)
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