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A074655 Number of Lyndon words (aperiodic necklaces) with 3n beads of 3 colors, n beads of each color. 1
1, 2, 14, 186, 2880, 50450, 952854, 19003474, 394394880, 8439756660, 185033201150, 4137181680698, 94020326259264, 2166105078791446, 50489825369325118, 1188777328563863850, 28236363841594782720, 675879582290807439794, 16289254212695836475436 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..18.

Index entries for sequences related to Lyndon words

FORMULA

a(n) = 1/(3n) * Sum_{d|n} mu(n/d) * (3d)! / d!^3, a(0) = 1.

CROSSREFS

a(n) = A029808(n)*2. a(n) = A074651(n)/3.

Sequence in context: A217905 A237852 A219874 * A268005 A158102 A067902

Adjacent sequences:  A074652 A074653 A074654 * A074656 A074657 A074658

KEYWORD

nonn

AUTHOR

Christian G. Bower, Aug 29 2002

EXTENSIONS

a(0)=1 prepended by Alois P. Heinz, Aug 24 2015

STATUS

approved

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Last modified November 13 15:41 EST 2019. Contains 329106 sequences. (Running on oeis4.)