cp's OEIS Frontend

A227061 T(n,k) = Number of (n+k-1) X (n+k-1) binary arrays with k 1s in every row and column with rows and columns in lexicographically nondecreasing order.

%I A227061 #9 Sep 12 2019 19:27:35
%S A227061 1,1,1,1,1,1,1,1,2,1,1,1,3,5,1,1,1,5,25,13,1,1,1,8,161,272,42,1,1,1,
%T A227061 13,1112,7776,4070,155,1,1,1,21,8787,287311,626649,79221,636,1,1,1,34,
%U A227061 76156,13704640,137393147,70821384,1906501,2889,1,1,1,55,728699,809171699
%N A227061 T(n,k) = Number of (n+k-1) X (n+k-1) binary arrays with k 1s in every row and column with rows and columns in lexicographically nondecreasing order.
%C A227061 Table starts
%C A227061 .1...1.....1......1......1....1.....1..1.1.1
%C A227061 .1...1.....1......1......1....1.....1..1.1
%C A227061 .1...2.....3......5......8...13....21.34
%C A227061 .1...5....25....161...1112.8787.76156
%C A227061 .1..13...272...7776.287311
%C A227061 .1..42..4070.626649
%C A227061 .1.155.79221
%C A227061 .1.636
%e A227061 Some solutions for n=4 k=4
%e A227061 ..0..0..0..1..1..1..1....0..0..0..1..1..1..1....0..0..0..1..1..1..1
%e A227061 ..0..1..1..0..0..1..1....0..1..1..0..0..1..1....0..0..0..1..1..1..1
%e A227061 ..0..1..1..0..1..0..1....0..1..1..0..1..0..1....0..1..1..0..0..1..1
%e A227061 ..1..0..0..1..0..1..1....1..0..0..1..1..1..0....1..0..0..1..1..0..1
%e A227061 ..1..0..1..1..1..0..0....1..0..1..0..0..1..1....1..1..1..0..0..1..0
%e A227061 ..1..1..0..1..0..1..0....1..1..0..1..1..0..0....1..1..1..0..1..0..0
%e A227061 ..1..1..1..0..1..0..0....1..1..1..1..0..0..0....1..1..1..1..0..0..0
%Y A227061 Column 2 is A229161(n+1).
%Y A227061 Column 3 is A229162(n+2).
%Y A227061 Column 4 is A229163(n+3).
%Y A227061 Column 5 is A229164(n+4).
%Y A227061 Row 3 is A000045(n+1).
%Y A227061 Row 4 is A181344(n+3).
%K A227061 nonn,tabl
%O A227061 1,9
%A A227061 _R. H. Hardin_ Sep 17 2013
%E A227061 More terms from _Sean A. Irvine_, Sep 12 2019