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 A208771 #10 Mar 19 2017 01:12:40 %S A208771 1,3,7,18,41,117,299,861,2413,6955,19943,57974,168013,489789,1428611, %T A208771 4177232,12226997,35847123,105200351,309086838,908931221,2675276801, %U A208771 7880255915,23228969891,68518137777,202231890207,597228362551,1764663912122 %N A208771 Number of n-bead necklaces labeled with numbers 1..n not allowing reversal, with no adjacent beads differing by more than 1. %H A208771 Andrew Howroyd, <a href="/A208771/b208771.txt">Table of n, a(n) for n = 1..100</a> %e A208771 All solutions for n=3: %e A208771 ..2....3....1....1....2....1....2 %e A208771 ..3....3....2....1....2....1....2 %e A208771 ..3....3....2....2....3....1....2 %Y A208771 Diagonal of A208777. %K A208771 nonn %O A208771 1,2 %A A208771 _R. H. Hardin_, Mar 01 2012 %E A208771 a(19)-a(28) from _Andrew Howroyd_, Mar 18 2017