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 A280676 #4 Jan 07 2017 08:11:07 %S A280676 14,612,12484,310365,7533245,183331502,4460317695,108520231044, %T A280676 2640298250694,64238619127022,1562929767205929,38026186043293995, %U A280676 925179685380850290,22509684536321285656,547662154172647585113 %N A280676 Number of 4Xn 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors and with new values introduced in order 0 sequentially upwards. %C A280676 Row 4 of A280673. %H A280676 R. H. Hardin, <a href="/A280676/b280676.txt">Table of n, a(n) for n = 1..210</a> %H A280676 R. H. Hardin, <a href="/A280676/a280676.txt"> Empirical recurrence of order 73</a> %F A280676 Empirical recurrence of order 73 (see link above) %e A280676 Some solutions for n=3 %e A280676 ..0..1..0. .0..0..1. .0..1..0. .0..0..1. .0..1..2. .0..1..2. .0..1..2 %e A280676 ..0..2..0. .1..2..1. .0..1..0. .1..0..1. .0..1..0. .0..2..1. .2..1..2 %e A280676 ..1..0..2. .2..1..2. .2..1..2. .2..1..0. .2..1..2. .1..2..0. .2..0..0 %e A280676 ..1..2..0. .0..0..2. .1..0..1. .0..2..0. .0..0..2. .0..1..2. .1..2..2 %Y A280676 Cf. A280673. %K A280676 nonn %O A280676 1,1 %A A280676 _R. H. Hardin_, Jan 07 2017