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 A213994 #5 Jul 22 2025 23:06:34 %S A213994 474286,35799856,421195466,5018010431,22406574462,124477495732, %T A213994 361204218672,1222761036532,3390266359632 %N A213994 Number of 5X5 0..n matrices whose square is also a 0..n matrix. %C A213994 Row 5 of A213990 %e A213994 Some solutions for n=3 %e A213994 ..0..2..1..0..1....0..1..1..0..3....1..1..3..2..0....0..0..3..0..0 %e A213994 ..0..0..0..1..0....0..0..1..0..0....0..0..0..1..3....0..1..1..3..3 %e A213994 ..0..1..0..1..0....0..2..0..1..1....0..0..0..0..0....0..0..0..0..0 %e A213994 ..0..0..1..0..0....0..0..1..0..0....1..0..0..0..0....1..0..0..0..0 %e A213994 ..0..0..0..0..0....0..0..0..0..0....0..0..0..1..1....0..0..0..0..0 %K A213994 nonn %O A213994 1,1 %A A213994 _R. H. Hardin_ Jun 30 2012