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A034301
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One quarter of quintic factorial numbers.
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13
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1, 9, 126, 2394, 57456, 1666224, 56651616, 2209413024, 97214173056, 4763494479744, 257228701906176, 15176493412464384, 971295578397720576, 67019394909442719744, 4959435223298761261056, 391795382640602139623424
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| 4*a(n) = (5*n-1)(!^5) := product(5*j-1, j=1..n) = (5*n)!/(5^n*n!*A008548(n)*2*A034323(n)*3*A034300(n)); E.g.f. (-1+(1-5*x)^(-4/5))/4, a(0) := 0.
a(n) ~ 5/4*2^(1/2)*pi^(1/2)*Gamma(4/5)^-1*n^(13/10)*5^n*e^-n*n^n*{1 + 241/300*n^-1 + ...}. - Joe Keane (jgk(AT)jgk.org), Nov 24 2001
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MATHEMATICA
| s=1; lst={s}; Do[s+=n*s; AppendTo[lst, s], {n, 8, 5!, 5}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 08 2008]
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CROSSREFS
| Cf. A008548, A034300, A025750.
Sequence in context: A144073 A065086 A065707 * A092651 A073014 A046754
Adjacent sequences: A034298 A034299 A034300 * A034302 A034303 A034304
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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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