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 A140918 Number of 3 X 9 matrices with elements in 0..n with each row and each column in nondecreasing order. 3,9,n can be permuted, see formula. 0

%I

%S 1,220,15730,572572,13026013,208416208,2530768240,24584605760,

%T 198520691512,1371597504992,8291930371088,44648855844320,

%U 217233856319480,966332582836544,3968865965221520,15175075749376400,54395951675154375,183902102876992500

%N Number of 3 X 9 matrices with elements in 0..n with each row and each column in nondecreasing order. 3,9,n can be permuted, see formula.

%F (empirical) set p,q,r to n,9,3 (in any order) in s=p+q+r-1; a(n) = product {i in 0..r-1} (binomial(s,p+i)*i!/(s-i)^(r-i-1))

%K nonn

%O 0,2

%A _R. H. Hardin_, Jul 05 2008

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Last modified December 5 03:52 EST 2021. Contains 349530 sequences. (Running on oeis4.)