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 A061545 #10 Dec 28 2024 10:20:06 %S A061545 0,2,1,1,1,2,4,16,40,512,1472,65536,208896 %N A061545 Number of pair-exchange / set-rotate sequences achieving the minimum length of A048200(n). %H A061545 Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a061/A061545.java">Java program</a> (github) %H A061545 Kevin Ryde, <a href="/A048200/a048200.c.txt">C Code</a> %e A061545 Let "r" denote rotation and "x" an exchange. %e A061545 For n = 5, the shortest sequence reversing "ABCDE" has length A048200(5) = 10, the only sequence doing so is "xrrxrrxrxr", so a(5) = 1. %e A061545 For n = 6, we have A048200(6) = 15, but there are 2 solutions of this length "xrxrrxrxrrxrrrx" and "rxrrxrxrrxrxrrx", so a(6) = 2. %o A061545 (Java) /* See links. */ %o A061545 (C) /* See links. */ %Y A061545 Cf. A048200, A378834 (LRE ways). %K A061545 more,nonn %O A061545 1,2 %A A061545 _Naohiro Nomoto_, May 16 2001 %E A061545 Sequence revised and a(9)-a(12) from _Sean A. Irvine_, Feb 21 2023 %E A061545 a(13) from _Kevin Ryde_, Dec 28 2024