Number of different ways to select n elements from two sets of n elements under the precondition of choosing at least one element from each set.
0, 4, 18, 68, 250, 922, 3430, 12868, 48618, 184754, 705430, 2704154, 10400598
3 seqfan posts
Sun Sep 5 13:08:02 CEST 2010 [seqfan] Re: A misprint in title of A086655
Wed Aug 25 11:03:46 CEST 2010 [seqfan] Just for fun, more tennis balls - addendum
Wed Aug 25 10:13:37 CEST 2010 [seqfan] Just for fun, more tennis balls
Index of A-numbers in seqfan: by ascending order
by month
by frequency
by keyword
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