Search: id:A059949
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%I A059949
%S A059949 0,0,0,0,0,535,51640,2771685,114713760,4127125695,136631722920,
%T A059949 4292250804985,130278290187760,3863262740532195,112733098867629240,
%U A059949 3252644718804860925,93093809127731630400,2649006256251644780935
%N A059949 Number of 8-block bicoverings of an n-set.
%D A059949 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, John Wiley 
               and Sons, N.Y., 1983.
%F A059949 a(n)=(1/8!)*(28^n-8*21^n-28*16^n+56*15^n+168*11^n-224*10^n+210*8^n-840*7^n+700*6^n-840*5^n+1925*4^n+1064*3^n-\
               5460*2^n+4368). E.g.f. for m-block bicoverings of an n-set is exp(-x-1/
               2*x^2*(exp(y)-1))*Sum_{i=0..inf} x^i/i!*exp(binomial(i, 2)*y).
%Y A059949 Cf. A002718, A059443, A003462, A059945-A059948, A059950-A059951.
%Y A059949 Sequence in context: A077085 A165989 A067723 this_sequence A077076 A033916 
               A111258
%Y A059949 Adjacent sequences: A059946 A059947 A059948 this_sequence A059950 A059951 
               A059952
%K A059949 easy,nonn
%O A059949 1,6
%A A059949 Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 14 2001

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