This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A187705 #6 Jul 22 2025 10:53:29 %S A187705 10,31,128,64,1489,2,113,8272,72,34,170,31461,322,5030,0,255,93476, %T A187705 1718,81456,36,2,336,235773,2904,875696,530,7410,0,449,524284,9834, %U A187705 4225652,4612,230446,474,0,570,1062857,13324,22532156,12898 %N A187705 T(n,k)=Number of (n+1)X(n+1) 0..k arrays with each 2X2 subblock off diagonal and antidiagonal nonsingular and the array of 2X2 subblock determinants antisymmetric about the diagonal and antidiagonal. %C A187705 Table starts %C A187705 ..10...31.....64....113.....170......255....336.....449.570 %C A187705 .128.1489...8272..31461...93476...235773.524284.1062857 %C A187705 ...2...72....322...1718....2904.....9834..13324 %C A187705 ..34.5030..81456.875696.4225652.22532156 %C A187705 ...0...36....530...4612...12898 %C A187705 ...2.7410.230446 %C A187705 ...0..474 %C A187705 ...0 %e A187705 Some k=3 solutions for 5X5 %e A187705 ..0..0..1..2..2....0..0..1..2..2....0..0..1..0..0....0..3..2..3..2 %e A187705 ..2..2..0..2..2....3..3..0..1..1....1..1..0..1..2....0..3..3..3..2 %e A187705 ..2..3..0..3..2....1..2..0..2..1....1..2..0..1..1....1..0..0..0..1 %e A187705 ..2..2..0..2..2....1..1..0..3..3....1..1..0..1..2....2..3..1..3..2 %e A187705 ..2..2..1..3..3....0..0..1..2..2....1..1..1..0..0....2..3..0..3..2 %Y A187705 Row 1 is A059306 %K A187705 nonn,tabl %O A187705 1,1 %A A187705 _R. H. Hardin_ Mar 12 2011