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 A209734 #7 Jul 22 2025 21:56:02 %S A209734 123480,6933120,420545824,27425792944,1809791149768,121396901813560, %T A209734 8142073013529816,548770608436244800,36942499122761432872, %U A209734 2491439485029085248096,167889440702169327824712 %N A209734 1/4 the number of (n+1)X7 0..3 arrays with every 2X2 subblock having distinct edge sums. %C A209734 Column 6 of A209736 %H A209734 R. H. Hardin, <a href="/A209734/b209734.txt">Table of n, a(n) for n = 1..210</a> %e A209734 Some solutions for n=4 %e A209734 ..3..1..3..1..0..3..3....3..0..1..1..2..2..3....1..1..1..0..1..1..3 %e A209734 ..3..2..3..2..2..2..0....2..2..2..3..3..0..3....2..3..2..0..3..2..3 %e A209734 ..3..0..3..1..0..1..0....3..0..1..1..2..2..2....1..3..1..0..1..0..1 %e A209734 ..2..0..2..1..3..1..3....2..0..2..3..3..0..1....0..2..1..3..3..3..1 %e A209734 ..2..3..3..1..0..0..0....1..0..1..1..2..2..2....0..3..1..2..1..2..1 %K A209734 nonn %O A209734 1,1 %A A209734 _R. H. Hardin_ Mar 12 2012