n-th Bell number of type D. A partition of {-n,...,-1,1,...,n} into nonempty subsets X_1,...,X_r is called `symmetric' if for each i -X_i = X_j for some j. a(n) is the number of such symmetric partitions such that none of the X_i are of the form {j,-j}.
1, 4, 15, 75, 428, 2781, 20093, 159340, 1372163, 12725447, 126238060
4 seqfan posts
Fri Apr 23 09:40:56 CEST 2010 [seqfan] Re: conjectured EGF and extension of A086365 and others
Fri Apr 16 10:34:33 CEST 2010 [seqfan] Re: conjectured EGF and extension of A086365 and others
Thu Apr 15 18:49:13 CEST 2010 [seqfan] Re: conjectured EGF and extension of A086365 and others
Thu Apr 15 17:34:39 CEST 2010 [seqfan] conjectured EGF and extension of A086365 and others
Index of A-numbers in seqfan: by ascending order
by month
by frequency
by keyword
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