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 A247535 #8 Nov 07 2018 11:29:21 %S A247535 8,61,220,561,1124,2009,3220,4901,7016,9737,13000,17025,21688,27245, %T A247535 33572,40929,49140,58553,68924,80613,93400,107641,123056,140113, %U A247535 158440,178509,200012,223393,248260,275209,303748,334453,366920,401689,438264 %N A247535 Number of length 3+3 0..n arrays with some disjoint pairs in every consecutive four terms having the same sum. %H A247535 R. H. Hardin, <a href="/A247535/b247535.txt">Table of n, a(n) for n = 1..210</a> %F A247535 Empirical: a(n) = a(n-2) + 2*a(n-3) + a(n-4) - 2*a(n-5) - 2*a(n-6) - 2*a(n-7) + a(n-8) + 2*a(n-9) + a(n-10) - a(n-12). %F A247535 Also as a cubic plus a linear quasipolynomial with period 12: %F A247535 Empirical for n mod 12 = 0: a(n) = (563/54)*n^3 - (127/18)*n^2 + 2*n + 1 %F A247535 Empirical for n mod 12 = 1: a(n) = (563/54)*n^3 - (127/18)*n^2 - (5/2)*n + (385/54) %F A247535 Empirical for n mod 12 = 2: a(n) = (563/54)*n^3 - (127/18)*n^2 + (10/9)*n + (97/27) %F A247535 Empirical for n mod 12 = 3: a(n) = (563/54)*n^3 - (127/18)*n^2 - (5/2)*n + (19/2) %F A247535 Empirical for n mod 12 = 4: a(n) = (563/54)*n^3 - (127/18)*n^2 + 2*n - (37/27) %F A247535 Empirical for n mod 12 = 5: a(n) = (563/54)*n^3 - (127/18)*n^2 - (61/18)*n + (761/54) %F A247535 Empirical for n mod 12 = 6: a(n) = (563/54)*n^3 - (127/18)*n^2 + 2*n - 1 %F A247535 Empirical for n mod 12 = 7: a(n) = (563/54)*n^3 - (127/18)*n^2 - (5/2)*n + (385/54) %F A247535 Empirical for n mod 12 = 8: a(n) = (563/54)*n^3 - (127/18)*n^2 + (10/9)*n + (151/27) %F A247535 Empirical for n mod 12 = 9: a(n) = (563/54)*n^3 - (127/18)*n^2 - (5/2)*n + (19/2) %F A247535 Empirical for n mod 12 = 10: a(n) = (563/54)*n^3 - (127/18)*n^2 + 2*n - (91/27) %F A247535 Empirical for n mod 12 = 11: a(n) = (563/54)*n^3 - (127/18)*n^2 - (61/18)*n + (761/54). %F A247535 Empirical g.f.: x*(8 + 61*x + 212*x^2 + 484*x^3 + 774*x^4 + 963*x^5 + 892*x^6 + 661*x^7 + 330*x^8 + 120*x^9 - x^11) / ((1 - x)^4*(1 + x)^2*(1 + x^2)*(1 + x + x^2)^2). - _Colin Barker_, Nov 07 2018 %e A247535 Some solutions for n=6: %e A247535 ..2....1....1....3....5....1....1....3....5....3....3....5....6....2....3....4 %e A247535 ..2....5....4....4....5....0....3....0....4....1....2....6....4....5....2....2 %e A247535 ..0....3....5....2....6....5....5....3....2....3....0....4....3....1....1....3 %e A247535 ..4....3....2....3....4....6....3....6....3....5....1....5....1....4....2....3 %e A247535 ..2....5....3....1....5....1....5....3....3....3....3....3....2....2....1....2 %e A247535 ..6....5....6....2....5....0....3....6....2....5....4....4....0....5....0....4 %Y A247535 Row 3 of A247533. %K A247535 nonn %O A247535 1,1 %A A247535 _R. H. Hardin_, Sep 18 2014