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A375105
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a(n) = (2*n)^(n-2)*(2*n)!/n!.
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0
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1, 12, 720, 107520, 30240000, 13795246080, 9302892318720, 8706006083174400, 10801536141415219200, 17163329863680000000000, 33994996578425904640819200, 82126085558902590463908249600, 237708952408715572102802964480000, 812136157489332816782291600670720000
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OFFSET
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1,2
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COMMENTS
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a(n) is the number of spanning trees with a perfect matching in a complete graph with 2*n nodes. See Li et al. in Links.
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LINKS
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FORMULA
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a(n) ~ (1/(2*sqrt(2)))*(8/e)^n*n^(2*(n-1)).
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MATHEMATICA
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a[n_]:=(2n)^(n-2)(2n)!/n!; Array[a, 14]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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