Quadruple factorial numbers: (2*n)!/n!.
1, 2, 12, 120, 1680, 30240, 665280, 17297280, 518918400, 17643225600
3 seqfan posts
Tue Aug 31 08:40:53 CEST 2010 [seqfan] Re: Permutation inverse = inversion
Mon Aug 30 12:32:29 CEST 2010 [seqfan] Re: Permutation inverse = inversion
Mon Aug 30 04:35:50 CEST 2010 [seqfan] Permutation inverse = inversion
Index of A-numbers in seqfan: by ascending order
by month
by frequency
by keyword
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