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 A212043 #6 Jun 02 2025 07:54:55 %S A212043 0,0,5,463,339764,65635205,3564578765,89579748909 %N A212043 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any element within a city block distance of two, and containing the value n(n+1)/2-6. %C A212043 Column 5 of A212044 %e A212043 Some solutions for n=4 %e A212043 ..0........0........0........0........0........0........0........0 %e A212043 ..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2 %e A212043 ..3.4.0....3.4.5....3.4.1....3.0.1....3.4.5....3.4.1....3.4.5....3.4.5 %e A212043 ..0.5.6.2..5.6.7.8..5.0.3.6..2.4.5.0..2.6.0.4..5.6.3.5..0.6.3.4..6.0.7.3 %K A212043 nonn %O A212043 1,3 %A A212043 _R. H. Hardin_ Apr 28 2012