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 A183711 #9 Oct 06 2015 21:56:47 %S A183711 2,17,224,5362,224640,16823812,2239265280,532844962952, %T A183711 226169896329216,171735135418632976,232966965220983791616, %U A183711 565591167958003196615968,2455196078535760615522467840 %N A183711 1/20 of the number of (n+1) X (n+1) 0..4 arrays with every 2 X 2 subblock strictly increasing clockwise or counterclockwise with one decrease. %C A183711 Diagonal of A183719. %e A183711 Some solutions for 3 X 3: %e A183711 ..0..1..0....3..2..3....2..3..1....4..3..0....4..0..4....4..0..3....0..1..0 %e A183711 ..3..2..3....4..0..4....1..4..0....1..2..1....2..1..2....2..1..2....4..3..4 %e A183711 ..4..1..0....3..2..3....2..3..1....0..3..0....3..0..3....3..4..3....1..2..1 %e A183711 ... %e A183711 ...R..L.......L..R.......R..L.......L..R.......R..L.......R..L.......R..L... %e A183711 ...L..R.......R..L.......L..R.......R..L.......L..R.......L..R.......L..R... %K A183711 nonn %O A183711 1,1 %A A183711 _R. H. Hardin_, Jan 06 2011