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 A240376 #6 Jun 02 2025 09:52:14 %S A240376 2,3,3,4,11,4,7,21,21,7,10,67,75,67,10,15,155,450,450,155,15,24,353, %T A240376 1729,5161,1729,353,24,35,998,7233,36398,36398,7233,998,35,54,2256, %U A240376 36148,271764,486179,271764,36148,2256,54,83,5639,139855,2492182,6436979 %N A240376 T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4. %C A240376 Table starts %C A240376 ..2.....3.......4..........7...........10............15.............24 %C A240376 ..3....11......21.........67..........155...........353............998 %C A240376 ..4....21......75........450.........1729..........7233..........36148 %C A240376 ..7....67.....450.......5161........36398........271764........2492182 %C A240376 .10...155....1729......36398.......486179.......6436979......110122847 %C A240376 .15...353....7233.....271764......6436979.....169838571.....5145071133 %C A240376 .24...998...36148....2492182....110122847....5145071133...296413962369 %C A240376 .35..2256..139855...17380978...1403151574..121626491919.12947745036751 %C A240376 .54..5639..645733..143489019..20729739995.3384817934297 %C A240376 .83.14624.2919837.1182292032.314460587672 %H A240376 R. H. Hardin, <a href="/A240376/b240376.txt">Table of n, a(n) for n = 1..111</a> %F A240376 Empirical for column k: %F A240376 k=1: a(n) = a(n-2) +2*a(n-3) %F A240376 k=2: [order 15] for n>17 %e A240376 Some solutions for n=4 k=4 %e A240376 ..3..2..3..3....3..3..2..3....2..2..3..2....3..3..2..3....3..2..3..3 %e A240376 ..2..0..1..2....3..2..0..3....2..1..1..0....3..1..2..1....2..1..1..2 %e A240376 ..3..1..2..1....2..0..2..0....3..1..2..1....2..2..2..2....3..3..2..0 %e A240376 ..2..1..1..2....3..1..0..2....2..0..2..2....2..0..0..0....2..1..2..0 %Y A240376 Column 1 is A159288(n+1) %K A240376 nonn,tabl %O A240376 1,1 %A A240376 _R. H. Hardin_, Apr 04 2014