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 A223819 #7 Jul 23 2025 04:33:56 %S A223819 4,4,16,22,112,172,1064,1742,11664,19976,138640,243802,1732272, %T A223819 3104312,22419608,40745940,297918608,547354320,4040882352,7488584886, %U A223819 55716851136,103984450924,778639744064,1461701983398,11004152490272,20759785009832 %N A223819 Number of nX1 0..3 arrays with every row and column least squares fitting to a zero slope straight line, with a single point array taken as having zero slope. %C A223819 Column 1 of A223824 %H A223819 R. H. Hardin, <a href="/A223819/b223819.txt">Table of n, a(n) for n = 1..199</a> %e A223819 Some solutions for n=4 %e A223819 ..0....0....2....3....3....2....1....2....1....3....2....1....1....2....3....0 %e A223819 ..0....3....2....1....0....0....0....1....2....3....3....0....1....0....2....3 %e A223819 ..0....0....2....1....3....0....0....1....2....3....3....3....1....3....2....3 %e A223819 ..0....1....2....3....2....2....1....2....1....3....2....0....1....1....3....0 %K A223819 nonn %O A223819 1,1 %A A223819 _R. H. Hardin_ Mar 27 2013