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 A213694 #5 Jun 02 2025 08:03:24 %S A213694 99,17499,16537086,83545858925,2256314178023600,325754552781442854792, %T A213694 251417716503635583550380605 %N A213694 Half the number of (n+1)X(n+1) symmetric 0..5 arrays with no 2X2 subblock summing to 10. %C A213694 Column 5 of A213697 %e A213694 Some solutions for n=4 %e A213694 ..1..4..4..1..0....3..3..2..3..3....2..4..3..0..4....2..3..1..0..3 %e A213694 ..4..3..1..5..2....3..3..0..4..1....4..4..1..3..5....3..3..2..2..4 %e A213694 ..4..1..0..3..3....2..0..3..4..4....3..1..5..2..2....1..2..5..0..0 %e A213694 ..1..5..3..2..3....3..4..4..0..5....0..3..2..2..3....0..2..0..2..3 %e A213694 ..0..2..3..3..5....3..1..4..5..2....4..5..2..3..3....3..4..0..3..3 %K A213694 nonn %O A213694 1,1 %A A213694 _R. H. Hardin_ Jun 18 2012