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 A259427 #6 Jun 02 2025 11:51:34 %S A259427 13,43,43,142,243,142,469,1366,1366,469,1549,7695,12953,7695,1549, %T A259427 5116,43347,123306,123306,43347,5116,16897,244228,1172659,1990133, %U A259427 1172659,244228,16897,55807,1376077,11155819,32060569,32060569,11155819,1376077 %N A259427 T(n,k)=Number of (n+1)X(k+1) 0..1 arrays with each 2X2 subblock having clockwise pattern 0000 0001 0011 or 0111. %C A259427 Table starts %C A259427 .....13.......43........142...........469............1549...............5116 %C A259427 .....43......243.......1366..........7695...........43347.............244228 %C A259427 ....142.....1366......12953........123306.........1172659...........11155819 %C A259427 ....469.....7695.....123306.......1990133........32060569..........516880938 %C A259427 ...1549....43347....1172659......32060569.......873754597........23840819225 %C A259427 ...5116...244228...11155819.....516880938.....23840819225......1101527291223 %C A259427 ..16897..1376077..106118138....8331704179....650266054724.....50866278137234 %C A259427 ..55807..7753553.1009466878..134312969201..17738788220867...2349427850331898 %C A259427 .184318.43687910.9602626846.2165188798924.483879193637566.108508759637883502 %H A259427 R. H. Hardin, <a href="/A259427/b259427.txt">Table of n, a(n) for n = 1..391</a> %F A259427 Empirical for column k: %F A259427 k=1: a(n) = 3*a(n-1) +a(n-2) %F A259427 k=2: a(n) = 6*a(n-1) +2*a(n-2) -22*a(n-3) -6*a(n-4) +6*a(n-5) +a(n-6) %F A259427 k=3: [order 8] %F A259427 k=4: [order 20] %F A259427 k=5: [order 32] %F A259427 k=6: [order 62] %e A259427 Some solutions for n=3 k=4 %e A259427 ..0..0..1..1..0....0..0..0..1..0....1..0..0..1..1....1..1..0..1..1 %e A259427 ..0..0..1..0..0....0..1..0..0..0....0..0..1..1..0....0..0..0..0..0 %e A259427 ..0..0..0..0..1....0..1..1..0..1....0..0..0..0..0....0..0..0..0..1 %e A259427 ..1..0..0..0..0....1..1..0..0..0....1..1..0..0..0....0..1..0..1..1 %Y A259427 Column 1 is A003688(n+2) %K A259427 nonn,tabl %O A259427 1,1 %A A259427 _R. H. Hardin_, Jun 26 2015