Search: id:A059951
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%I A059951
%S A059951 0,0,0,0,0,0,420,154637,20368816,1775801814,124151410020,7596257673279,
%T A059951 426319554841752,22564352299016528,1146221298547133380,
%U A059951 56531610963314602401,2728475248127447671008,129586638359127411410442
%N A059951 10-block bicoverings of an n-set.
%D A059951 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, John Wiley 
               and Sons, N.Y., 1983.
%F A059951 a(n)=(1/10!)*(45^n-10*36^n-45*29^n+90*28^n+360*22^n-480*21^n+630*17^n-2520*16^n+2100*15^n-3780*12^n+10080*11^\
               n-6552*10^n-3150*9^n+18900*8^n-31500*7^n+28560*6^n-46620*5^n+27720*4^n+85560*3^n-146160*2^n+83520). 
               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 A059951 Cf. A002718, A059443, A003462, A059945-A059950.
%Y A059951 Sequence in context: A135380 A035846 A046167 this_sequence A028683 A014890 
               A159589
%Y A059951 Adjacent sequences: A059948 A059949 A059950 this_sequence A059952 A059953 
               A059954
%K A059951 easy,nonn
%O A059951 1,7
%A A059951 Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 14 2001

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