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 A187463 #7 Jul 22 2025 10:46:31 %S A187463 26,1236,13726,84048,325932,1118854,2843394,6976192,14900828,30426976, %T A187463 54176690,102373984,165774050,274508960,439528372,685793860,988022550, %U A187463 1499573556,2077344368,3019161806,4198346324,5736736398,7500683014 %N A187463 Number of 3X3 0..n arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric. %C A187463 Row 2 of A187462 %H A187463 R. H. Hardin, <a href="/A187463/b187463.txt">Table of n, a(n) for n = 1..40</a> %K A187463 nonn %O A187463 1,1 %A A187463 _R. H. Hardin_ Mar 10 2011