# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a187405 Showing 1-1 of 1 %I A187405 #4 Mar 31 2012 12:36:08 %S A187405 36,4332,2164680,4935992256,54448184779776,3028538328016591872 %N A187405 Number of (n+1)X(n+1) 0..5 arrays with diagonal zero and the i,j-th 2X2 subblock sum equal to the j,i-th 2X2 subblock sum %C A187405 Column 5 of A187408 %e A187405 Some solutions for 4X4 %e A187405 ..0..3..0..3....0..3..3..1....0..3..3..3....0..3..3..3....0..0..0..3 %e A187405 ..1..0..2..4....3..0..0..2....2..0..4..1....5..0..4..1....0..0..4..1 %e A187405 ..0..4..0..4....2..1..0..1....4..4..0..3....1..4..0..5....2..2..0..0 %e A187405 ..4..1..5..0....2..1..1..0....1..2..2..0....3..3..3..0....3..1..2..0 %K A187405 nonn %O A187405 1,1 %A A187405 _R. H. Hardin_ Mar 09 2011 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE