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A193282
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(n!/floor(n/2)!)^2
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1
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1, 1, 4, 36, 144, 3600, 14400, 705600, 2822400, 228614400, 914457600, 110649369600, 442597478400, 74798973849600, 299195895398400, 67319076464640000, 269276305858560000, 77820852393123840000, 311283409572495360000, 112373310855670824960000
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OFFSET
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0,3
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..400
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FORMULA
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a(n) = A056040(n)*A000142(n).
a(n) = A081125(n)^2.
a(n) = sum(k=0..n, (-1)^(n-k)*binomial(n,k)*A195009(n,k)).
a(n) = n!^2*[x^n] (1+x)*BesselI(0,2*x). Here [x^n]f(x) denotes the coefficient of x^n in f(x).
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MAPLE
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A193282 := n -> (n!/iquo(n, 2)!)^2;
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PROG
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(MAGMA) [(Factorial(n)/Factorial(Floor(n/2)))^2: n in [0..20]]; // Vincenzo Librandi, Sep 11 2011
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CROSSREFS
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Cf. A000142, A056040, A195009.
Sequence in context: A069046 A065886 A069053 * A192217 A186434 A034569
Adjacent sequences: A193279 A193280 A193281 * A193283 A193284 A193285
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KEYWORD
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nonn
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AUTHOR
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Peter Luschny, Sep 08 2011
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STATUS
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approved
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