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 A245947 #8 Nov 05 2018 06:33:04 %S A245947 834,3966,18384,82968,381222,1744494,7972932,36489120,166920402, %T A245947 763564758,3493201536,15980209872,73104350502,334430964150, %U A245947 1529917916484,6998905422984,32017855579074,146471872453902,670063969035792 %N A245947 Number of length n+3 0..5 arrays with some pair in every consecutive four terms totalling exactly 5. %H A245947 R. H. Hardin, <a href="/A245947/b245947.txt">Table of n, a(n) for n = 1..210</a> %F A245947 Empirical: a(n) = 3*a(n-1) + 5*a(n-2) + 13*a(n-3) - 13*a(n-4) - a(n-5) - 3*a(n-6) + a(n-7). %F A245947 Empirical g.f.: 6*x*(139 + 244*x + 386*x^2 - 476*x^3 - 53*x^4 - 102*x^5 + 36*x^6) / (1 - 3*x - 5*x^2 - 13*x^3 + 13*x^4 + x^5 + 3*x^6 - x^7). - _Colin Barker_, Nov 05 2018 %e A245947 Some solutions for n=4: %e A245947 ..0....5....4....3....1....0....1....3....5....0....3....4....5....3....3....0 %e A245947 ..4....1....1....2....2....4....4....5....0....2....0....5....0....3....3....3 %e A245947 ..5....5....1....2....4....0....5....1....2....3....1....2....4....3....5....2 %e A245947 ..3....0....0....5....5....5....4....4....2....1....4....0....4....2....0....1 %e A245947 ..0....4....4....3....3....3....0....3....5....2....3....1....1....5....5....1 %e A245947 ..0....1....3....1....2....1....0....0....0....1....2....4....4....1....5....4 %e A245947 ..2....3....1....0....0....0....5....2....3....4....5....3....4....0....0....5 %Y A245947 Column 5 of A245950. %K A245947 nonn %O A245947 1,1 %A A245947 _R. H. Hardin_, Aug 08 2014