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a(n)=0!*1!*2!*3!*4!*(5*n)!*10*n*(n-1) / ((n)!*(n+1)!*(n+2)!*(n+3)!*(n+4)!)
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%I #3 Mar 31 2012 12:35:49

%S 0,840,360360,199536480,140229804000,118949931243000,

%T 117015012361447200,129624266420759510400,158211402715245473193600,

%U 209298196564031904834960000,296336346592302886974184080000

%N a(n)=0!*1!*2!*3!*4!*(5*n)!*10*n*(n-1) / ((n)!*(n+1)!*(n+2)!*(n+3)!*(n+4)!)

%C (Empirical) Number of nX5 matrices containing a defective permutation of 1..5*n in strictly increasing order rowwise and columnwise, with one permutation value omitted and one repeated (see example)

%C Column 5 of A181204

%H R. H. Hardin, <a href="/A181203/b181203.txt">Table of n, a(n) for n=1..50</a>

%e Some solutions for 2X5

%e ..1..4..5..6..8....1..2..4..7..9....1..3..5..8..9....1..2..5..6..8

%e ..3..5..7..9.10....5..6..8..9.10....4..6..7..9.10....3..4..8..9.10

%K nonn

%O 1,2

%A _R. H. Hardin_ Oct 10 2010