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 A245949 #7 Nov 05 2018 06:32:55 %S A245949 2216,13064,73728,397504,2217096,12257032,67596992,373997376, %T A245949 2066660136,11420014856,63122102528,348845096320,1927940409608, %U A245949 10655229621512,58887811241024,325454196462720,1798683415254952,9940745874984456 %N A245949 Number of length n+3 0..7 arrays with some pair in every consecutive four terms totalling exactly 7. %H A245949 R. H. Hardin, <a href="/A245949/b245949.txt">Table of n, a(n) for n = 1..210</a> %F A245949 Empirical: a(n) = 3*a(n-1) + 9*a(n-2) + 31*a(n-3) - 19*a(n-4) - 3*a(n-5) - 5*a(n-6) + a(n-7). %F A245949 Empirical g.f.: 8*x*(277 + 802*x + 1824*x^2 - 1244*x^3 - 231*x^4 - 312*x^5 + 64*x^6) / (1 - 3*x - 9*x^2 - 31*x^3 + 19*x^4 + 3*x^5 + 5*x^6 - x^7). - _Colin Barker_, Nov 05 2018 %e A245949 Some solutions for n=3: %e A245949 ..5....4....0....5....0....4....3....5....6....2....4....6....5....3....7....3 %e A245949 ..3....1....1....2....2....1....2....4....1....4....3....2....0....4....2....5 %e A245949 ..2....6....7....3....3....3....6....1....2....7....0....3....7....1....4....3 %e A245949 ..5....5....2....3....5....5....1....6....5....0....7....1....6....0....5....2 %e A245949 ..4....0....5....4....3....4....7....3....5....2....6....4....5....7....3....4 %e A245949 ..0....1....6....6....2....3....1....2....6....4....6....7....0....4....7....2 %Y A245949 Column 7 of A245950. %K A245949 nonn %O A245949 1,1 %A A245949 _R. H. Hardin_, Aug 08 2014