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Search: id:A151932
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| A151932 |
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a(n) = 2^(2*n)*(n!)^2*Prod_{e_k} binomial(2*e_k, e_k) where 2n = Prod p_k^e_k is the prime factorization of 2n. |
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2
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| 8, 384, 9216, 2949120, 58982400, 25480396800, 1664719257600, 7457942274048000, 414235422307123200, 165694168922849280000, 26731992586219683840000, 153976277296625378918400000
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Floris P. van Doorn and Jasper Mulder, Table of n, a(n) for n=1,...,250.
Reinhardt Wiewe, Most-perfect magic squares (4)
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EXAMPLE
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n = 5: 2n = 10 = 2^1*5^1, a(5) = 2^10*120^2*2*2 = 58982400.
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MATHEMATICA
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Array[2^(2#) (#!)^2 Times@@(Binomial[2#, # ]&/@FactorInteger[2# ][[All, 2]])&, 12] [From Floris P. van Doorn and Jasper Mulder (florisvandoorn(AT)hotmail.com), Oct 12 2009]
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CROSSREFS
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Sequence in context: A167256 A038016 A072447 this_sequence A096205 A162445 A067624
Adjacent sequences: A151929 A151930 A151931 this_sequence A151933 A151934 A151935
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KEYWORD
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nonn,more,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Aug 11 2009
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EXTENSIONS
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More terms from Floris P. van Doorn and Jasper Mulder (florisvandoorn(AT)hotmail.com), Oct 12 2009
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