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 A245946 #6 Apr 26 2021 19:28:33 %S A245946 453,1889,7769,31465,128649,525041,2141609,8740385,35666177,145538749, %T A245946 593901081,2423511809,9889552885,40356071813,164679993617, %U A245946 672005573917,2742236755101,11190178304945,45663487141625,186337877072653 %N A245946 Number of length n+3 0..4 arrays with some pair in every consecutive four terms totalling exactly 4. %C A245946 Column 4 of A245950. %H A245946 R. H. Hardin, <a href="/A245946/b245946.txt">Table of n, a(n) for n = 1..210</a> %F A245946 Empirical: a(n) = 3*a(n-1) +5*a(n-2) +3*a(n-3) -10*a(n-4) -37*a(n-5) -48*a(n-6) -37*a(n-7) +83*a(n-8) +143*a(n-9) +5*a(n-10) -11*a(n-11) -41*a(n-12) -10*a(n-13) -2*a(n-14) +3*a(n-15). %e A245946 Some solutions for n=5 %e A245946 ..0....4....2....1....1....0....0....0....1....0....1....2....2....1....3....4 %e A245946 ..1....0....2....1....3....0....4....0....1....3....4....0....1....4....1....1 %e A245946 ..4....3....0....0....4....3....0....4....3....1....3....1....3....3....0....3 %e A245946 ..3....3....2....4....0....1....1....3....1....3....2....4....4....0....2....4 %e A245946 ..1....1....3....0....0....1....2....3....2....1....1....4....0....0....3....2 %e A245946 ..2....2....2....4....4....4....2....0....2....3....0....0....1....1....2....2 %e A245946 ..2....0....2....4....2....0....0....4....3....3....3....0....0....3....1....4 %e A245946 ..4....4....0....3....1....0....4....1....3....0....4....2....4....0....2....2 %Y A245946 Cf. A245950. %K A245946 nonn %O A245946 1,1 %A A245946 _R. H. Hardin_, Aug 08 2014