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A093458
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Mixed factorials. Define MF(n) as the product prime(1)*composite(1)*(prime(2)*composite(2)...prime(n/2)*composite(n/2) if n is even else MF(n) as the product prime(1)*composite(1)*(prime(2)*composite(2)*...*prime((n+1)/2). a(0)= 1.
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1
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1, 2, 8, 24, 144, 720, 5760, 40320, 362880, 3991680, 39916800, 518918400, 6227020800, 105859353600, 1482030950400, 28158588057600, 422378820864000, 9714712879872000, 155435406077952000, 4507626776260608000
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OFFSET
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1,2
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COMMENTS
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Partial product of A073846.
a(n-1) is the number of elements in the largest conjugacy class of A_n, the alternating group on n letters. Cf. A059171. [Geoffrey Critzer, Mar 26 2013]
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LINKS
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Table of n, a(n) for n=1..20.
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MATHEMATICA
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g[list_]:=Total[list]!/Apply[Times, list]/Apply[Times, Table[Count[list, n]!, {n, 1, 20}]]; f[list_]:=Apply[Plus, Table[Count[list, n], {n, 2, 20, 2}]]; Drop[Table[Max[Map[g, Select[Partitions[n], EvenQ[f[#]]&]]], {n, 1, 20}]] (* Geoffrey Critzer, Mar 26 2013 *)
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CROSSREFS
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Cf. A073846, A093459.
Sequence in context: A087982 A176475 A145238 * A088994 A214849 A141598
Adjacent sequences: A093455 A093456 A093457 * A093459 A093460 A093461
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KEYWORD
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less,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 03 2004
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EXTENSIONS
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More terms from David Wasserman, Sep 28 2006
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STATUS
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approved
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