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 A265931 #6 Dec 19 2015 09:51:37 %S A265931 125,4616,17936,72772,273616,1042020,3883480,14617920,55503312, %T A265931 210277584,791400360,2978940280,11257286824,42533780480,160460490488, %U A265931 604824610736,2282902792488,8619222724444,32528290390168,122688090414988 %N A265931 Number of 3Xn 0..4 arrays with the absolute differences of each element with its with horizontal and antidiagonal neighbors unique. %C A265931 Row 3 of A265928. %H A265931 R. H. Hardin, <a href="/A265931/b265931.txt">Table of n, a(n) for n = 1..210</a> %e A265931 Some solutions for n=4 %e A265931 ..0..0..4..3....4..1..0..4....1..3..3..4....1..3..0..1....1..4..0..0 %e A265931 ..3..4..1..1....3..0..4..1....4..0..0..1....3..0..4..3....4..3..3..4 %e A265931 ..2..2..4..0....1..3..0..0....2..3..3..0....2..2..1..4....1..1..4..3 %Y A265931 Cf. A265928. %K A265931 nonn %O A265931 1,1 %A A265931 _R. H. Hardin_, Dec 18 2015