Search: id:A055603
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%I A055603
%S A055603 0,1,90,2248,43000,755100,13003620,226262400,4037765760,74481120000
%N A055603 Number of n X n binary matrices with no zero rows or columns and with 
               n+2 ones.
%F A055603 Number of m X n binary matrices with no zero rows or columns and with 
               k=0..m*n ones is Sum_{i=0..n} (-1)^i*C(n, i)*a(m, n-i, k) where a(m, 
               n, k)=Sum_{i=0..m} (-1)^i*C(m, i)*C((m-i)*n, k).
%F A055603 a(n) = n*(n-1)*(9*n^4+42*n^3+7*n^2-122*n-120)*n!/576. - Vladeta Jovovic 
               (vladeta(AT)eunet.rs), Mar 25 2006
%Y A055603 A diagonal of triangle A104601.
%Y A055603 Cf. A055602.
%Y A055603 Sequence in context: A060094 A065951 A008393 this_sequence A109124 A013359 
               A013355
%Y A055603 Adjacent sequences: A055600 A055601 A055602 this_sequence A055604 A055605 
               A055606
%K A055603 nonn
%O A055603 1,3
%A A055603 Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 01 2000

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