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 A222837 #6 Jul 23 2025 03:08:05 %S A222837 163,6144,5832,10584,22848,55296,138240,301056,642048,1382400,3022848, %T A222837 6690816,14816256,32741376,72244224,159258624,351111168,774297600, %U A222837 1707764736,3766818816,8308300800,18324658176,40416165888,89140107264 %N A222837 Number of nX7 0..3 arrays with no element equal to another at a city block distance of exactly two, and new values 0..3 introduced in row major order. %C A222837 Column 7 of A222838 %H A222837 R. H. Hardin, <a href="/A222837/b222837.txt">Table of n, a(n) for n = 1..64</a> %F A222837 Empirical: a(n) = 2*a(n-1) +a(n-3) -2*a(n-4) +4*a(n-5) +a(n-6) -a(n-9) for n>14 %e A222837 Some solutions for n=4 %e A222837 ..0..1..2..2..3..1..2....0..1..1..2..0..0..1....0..1..1..2..3..1..2 %e A222837 ..2..3..0..0..3..1..0....3..3..0..2..3..3..1....0..3..3..2..0..0..2 %e A222837 ..2..3..1..1..2..2..3....1..2..0..1..1..2..0....1..2..0..1..1..3..3 %e A222837 ..1..0..2..3..0..0..3....1..2..3..3..0..2..3....3..2..0..3..2..2..1 %K A222837 nonn %O A222837 1,1 %A A222837 _R. H. Hardin_ Mar 06 2013