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 A212833 #7 Jul 22 2025 22:58:29 %S A212833 2,17,178,2309,35954,654797,13667858,321839625,8441614754, %T A212833 244108628489,7716226532642,264711412437133,9795540525116306, %U A212833 388938430069794373,16494335589910579186,744110964577292267537,35582626582915655239234 %N A212833 Number of 0..n arrays of length n+1 with 0 never adjacent to n. %C A212833 Diagonal of A212835 %H A212833 R. H. Hardin, <a href="/A212833/b212833.txt">Table of n, a(n) for n = 1..210</a> %e A212833 Some solutions for n=5 %e A212833 ..0....4....1....1....5....4....3....4....5....3....3....3....0....4....5....2 %e A212833 ..0....1....1....2....1....3....3....0....2....5....3....2....1....3....1....4 %e A212833 ..1....1....1....1....1....5....5....2....5....3....2....0....3....1....2....2 %e A212833 ..3....0....5....3....3....3....1....1....2....5....5....3....4....0....0....5 %e A212833 ..4....4....2....2....0....3....2....1....5....2....2....0....3....1....4....3 %e A212833 ..1....3....0....4....3....4....5....2....1....1....4....1....3....2....2....1 %K A212833 nonn %O A212833 1,1 %A A212833 _R. H. Hardin_ May 28 2012