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 A195525 #7 Jul 22 2025 12:45:14 %S A195525 505623,839301197,122092290831,5151383545261,103074513713971, %T A195525 1252997799222737,10665939121760907,69488770600802237, %U A195525 367679036207885407,1647079991451268941,6438544930173240123,22466897655527435065 %N A195525 Number of lower triangles of a 7X7 -n..n array with all row and column sums zero. %C A195525 Row 7 of A195522 %H A195525 R. H. Hardin, <a href="/A195525/b195525.txt">Table of n, a(n) for n = 1..14</a> %e A195525 Some solutions for n=4 %e A195525 ..0..............0..............0..............0..............0 %e A195525 .-4.4...........-4.4............3-3...........-2.2...........-4.4 %e A195525 ..1.2-3..........2-3.1..........3-2-1.........-2.1.1.........-2.0.2 %e A195525 ..4-1-1-2.......-3-3.3.3........2-1.1-2.......-4-1.1.4........4.3-3-4 %e A195525 .-1-1.2.2-2......3-3-1-1.2.....-2.2.1.3-4......3-2.2.0-3.....-1-4-3.4.4 %e A195525 .-2-3.2-1.3.1...-1.3-3.0-3.4...-2.3.2-4.4-3....2-4.0-1.2.1....1.0.0.3-3-1 %e A195525 ..2-1.0.1-1-1.0..3.2.0-2.1-4.0.-4.1-3.3.0.3.0..3.4-4-3.1-1.0..2-3.4-3-1.1.0 %K A195525 nonn %O A195525 1,1 %A A195525 _R. H. Hardin_ Sep 20 2011