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 A187625 #7 Jul 22 2025 10:50:27 %S A187625 24,446,2924,12104,37448,98014,221640,457632,871712,1562702,2649632, %T A187625 4329136,6782660,10323450,15291860,22111560,31246860,43422938, %U A187625 59215112,79658992,105617736,138251814,178796912,229108212,290437464,364933542 %N A187625 Number of 3X3 0..n arrays with each 2X2 non-center subblock determinant nonzero and the array of 2X2 subblock determinants antisymmetric under 90 degree rotation. %C A187625 Row 2 of A187624 %H A187625 R. H. Hardin, <a href="/A187625/b187625.txt">Table of n, a(n) for n = 1..35</a> %e A187625 Some n=3 solutions for 3X3 %e A187625 ..3..0..3....3..0..3....2..2..2....1..3..0....1..1..3....0..2..3....1..3..1 %e A187625 ..3..3..0....0..2..3....1..3..1....1..0..1....1..0..1....1..0..1....2..3..2 %e A187625 ..3..0..3....3..0..3....2..2..2....3..3..1....0..1..3....1..2..2....1..3..1 %K A187625 nonn %O A187625 1,1 %A A187625 _R. H. Hardin_ Mar 12 2011