Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #2 Mar 30 2012 16:51:55
%S 2,20,188,1222,6872,35954,180070
%N Total number of balls in room in variant of the tennis ball problem (cf. A171074);
%C Apparently equals A051133(n) - A090288(n-1) after 1st term.
%C Note that A051133 yields the totals of all C(2n, n) ball sets and A005893 and A090288 are the respective totals of impossible combinations given the rules.
%D David Scambler, Just for fun, more tennis balls, Posting to the Sequence Fans Mailing List, Aug 25 2010.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Sep 06 2010