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 A183713 #11 Apr 04 2018 10:48:04 %S A183713 12,54,224,950,4012,16964,71712,303170,1281664,5418314,22906232, %T A183713 96837444,409385940,1730703022,7316648160,30931557950,130764969444, %U A183713 552816553732,2337064300200,9880075964922,41768598769664,176579193270290 %N A183713 1/20 of the number of (n+1) X 4 0..4 arrays with every 2 X 2 subblock strictly increasing clockwise or counterclockwise with one decrease. %C A183713 Column 3 of A183719. %H A183713 R. H. Hardin, <a href="/A183713/b183713.txt">Table of n, a(n) for n = 1..200</a> %F A183713 Empirical: a(n) = 2*a(n-1) + 10*a(n-2) - 10*a(n-4) - 2*a(n-5) + a(n-6). %F A183713 Empirical g.f.: 2*x*(6 + 15*x - 2*x^2 - 19*x^3 - 4*x^4 + 2*x^5) / ((1 - x)*(1 + x)*(1 - 2*x - 9*x^2 - 2*x^3 + x^4)). - _Colin Barker_, Apr 04 2018 %e A183713 Some solutions for 3 X 4: %e A183713 ..0..4..1..4....0..4..0..4....4..0..4..0....3..0..3..4....3..2..3..2 %e A183713 ..2..3..2..3....1..2..1..3....3..2..3..2....2..1..2..0....0..1..0..1 %e A183713 ..0..4..1..0....0..3..0..4....0..1..4..0....3..4..3..4....3..2..4..2 %e A183713 ... %e A183713 ...L..R..L.......L..R..L.......R..L..R.......R..L..R.......L..R..L... %e A183713 ...R..L..R.......R..L..R.......L..R..L.......L..R..L.......R..L..R... %Y A183713 Cf. A183719. %K A183713 nonn %O A183713 1,1 %A A183713 _R. H. Hardin_, Jan 06 2011