cp's OEIS Frontend

A188401 Number of (7*n) X 7 binary arrays with rows in nonincreasing order, n ones in every column and no more than 2 ones in any row.

%I A188401 #9 Apr 07 2020 15:03:15
%S A188401 1,232,22054,902962,20758650,313568636,3444274966,29445929253,
%T A188401 205617134345,1214911142900,6238854236951,28428076580526,
%U A188401 116844463511314,438968651731176,1523790358321400,4931487866349689,14991891923697588,43084786003434739,117690415289036999
%N A188401 Number of (7*n) X 7 binary arrays with rows in nonincreasing order, n ones in every column and no more than 2 ones in any row.
%C A188401 Number of 7 X 7 symmetric matrices with nonnegative integer entries and all row and column sums n. - _Andrew Howroyd_, Apr 07 2020
%H A188401 Andrew Howroyd, <a href="/A188401/b188401.txt">Table of n, a(n) for n = 0..30</a>
%e A188401 Some solutions for 14X7
%e A188401 ..1..1..0..0..0..0..0....1..1..0..0..0..0..0....1..1..0..0..0..0..0
%e A188401 ..1..0..0..0..0..0..0....1..0..0..0..0..0..1....1..0..0..1..0..0..0
%e A188401 ..0..1..0..0..1..0..0....0..1..0..1..0..0..0....0..1..0..0..1..0..0
%e A188401 ..0..0..1..1..0..0..0....0..0..1..0..0..0..0....0..0..1..0..0..0..0
%e A188401 ..0..0..1..0..0..0..0....0..0..1..0..0..0..0....0..0..1..0..0..0..0
%e A188401 ..0..0..0..1..0..0..0....0..0..0..1..0..1..0....0..0..0..1..0..1..0
%e A188401 ..0..0..0..0..1..0..1....0..0..0..0..1..0..0....0..0..0..0..1..0..0
%e A188401 ..0..0..0..0..0..1..0....0..0..0..0..1..0..0....0..0..0..0..0..1..0
%e A188401 ..0..0..0..0..0..1..0....0..0..0..0..0..1..1....0..0..0..0..0..0..1
%e A188401 ..0..0..0..0..0..0..1....0..0..0..0..0..0..0....0..0..0..0..0..0..1
%e A188401 ..0..0..0..0..0..0..0....0..0..0..0..0..0..0....0..0..0..0..0..0..0
%e A188401 ..0..0..0..0..0..0..0....0..0..0..0..0..0..0....0..0..0..0..0..0..0
%e A188401 ..0..0..0..0..0..0..0....0..0..0..0..0..0..0....0..0..0..0..0..0..0
%e A188401 ..0..0..0..0..0..0..0....0..0..0..0..0..0..0....0..0..0..0..0..0..0
%Y A188401 Column 7 of A188403.
%K A188401 nonn
%O A188401 0,2
%A A188401 _R. H. Hardin_, Mar 30 2011
%E A188401 a(0)=1 prepended and terms a(11) and beyond from _Andrew Howroyd_, Apr 07 2020