[seqfan] Re: Counting binary matrices - can these really be new?

[Ron Hardin]

Doing a fast table
/tmp/djl
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
Table starts
.1...1....1....1....1....1..1.1.1
.1...1....1....1....1....1..1.1..
.1...2....3....5....8...13.21....
.1...5...25..161.1112.8787.......
.1..13..272.7776.................
.1..42.4070......................
.1.155...........................
.1...............................


turns up http://oeis.org/A181344 as row 4

 
rhhardin at mindspring.com
rhhardin at att.net (either)