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%I #8 Nov 10 2014 17:35:12
%S 2,12,271,24950,9800058,16942485560,131898088386405,
%T 4704783844260626244
%N Number of n X n nonnegative integer matrices with row and column i=1..n having sum <= i.
%C Column 1 of A214011.
%e Some solutions for n=3:
%e ..1..0..0....0..1..0....0..0..0....0..1..0....0..0..0....0..1..0....0..0..1
%e ..0..1..1....0..1..0....0..0..1....1..0..0....0..1..1....0..0..1....1..0..0
%e ..0..0..2....0..0..1....0..0..2....0..1..0....0..0..1....0..0..0....0..0..1
%Y Cf. A214011.
%K nonn,more
%O 1,1
%A _R. H. Hardin_, Jun 30 2012