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 A249984 #8 Nov 10 2018 05:46:27 %S A249984 64,384,1242,3030,6252,11524,19574,31242,47480,69352,98034,134814, %T A249984 181092,238380,308302,392594,493104,611792,750730,912102,1098204, %U A249984 1311444,1554342,1829530,2139752,2487864,2876834,3309742,3789780,4320252,4904574 %N A249984 Number of length 4+1 0..2*n arrays with the sum of the absolute values of adjacent differences equal to 4*n. %H A249984 R. H. Hardin, <a href="/A249984/b249984.txt">Table of n, a(n) for n = 1..210</a> %F A249984 Empirical: a(n) = (14/3)*n^4 + (56/3)*n^3 + (121/3)*n^2 - (5/3)*n + 2. %F A249984 Conjectures from _Colin Barker_, Nov 10 2018: (Start) %F A249984 G.f.: 2*x*(32 + 32*x - 19*x^2 + 10*x^3 + x^4) / (1 - x)^5. %F A249984 a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5. %F A249984 (End) %e A249984 Some solutions for n=6: %e A249984 ..3...12....2....1....6....9...12....2....8...12....3....2...11...12....2....2 %e A249984 ..0....0....9...11....2....3....2...11....0....6...11....6...12....1...12....9 %e A249984 .12....6....1....8...10....8...10....9....9...11....0...12....0....7....3....1 %e A249984 .10....6....1....0....5....2....6...11....3....0....1....5....4....2....7....3 %e A249984 ..3....0...10....3...12....9....8....0....4....2....5...12...11....0....6...10 %Y A249984 Row 4 of A249982. %K A249984 nonn %O A249984 1,1 %A A249984 _R. H. Hardin_, Nov 10 2014