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 A061545 Number of pair-exchange / set-rotate sequences achieving the minimum length of A048200(n). 1
 0, 2, 1, 1, 1, 2, 4, 16, 40, 512, 1472, 65536 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..12. Sean A. Irvine, Java program (github) EXAMPLE Let "r" denote rotation and "x" an exchange. For n = 5, the shortest sequence reversing "ABCDE" has length A048200(5) = 10, the only sequence doing so is "xrrxrrxrxr", so a(5) = 1. For n = 6, we have A048200(6) = 15, but there are 2 solutions of this length "xrxrrxrxrrxrrrx" and "rxrrxrxrrxrxrrx", so a(6) = 2. CROSSREFS Cf. A048200. Sequence in context: A246576 A358273 A215894 * A287641 A265312 A241531 Adjacent sequences: A061542 A061543 A061544 * A061546 A061547 A061548 KEYWORD more,nonn AUTHOR Naohiro Nomoto, May 16 2001 EXTENSIONS Sequence revised and a(9)-a(12) from Sean A. Irvine, Feb 21 2023 STATUS approved

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Last modified September 9 11:20 EDT 2024. Contains 375764 sequences. (Running on oeis4.)