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A200919 Number of crossings on periodic braids with n strands such that all strands meet. 1
0, 0, 0, 1, 3, 5, 9, 13, 19, 25, 34 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..11.

Duraid Madina, Illustration of initial terms a(1) .. a(7)

N. J. A. Sloane, Illustration for a(6) = 5

CROSSREFS

Sequence in context: A209974 A099392 A080827 * A213207 A102378 A118026

Adjacent sequences:  A200916 A200917 A200918 * A200920 A200921 A200922

KEYWORD

nonn,hard,nice,more

AUTHOR

Duraid Madina, Nov 24 2011

EXTENSIONS

a(11) added by Duraid Madina, Oct 03 2012

a(7) corrected by Duraid Madina, Dec 11 2012

STATUS

approved

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Last modified August 3 22:03 EDT 2021. Contains 346441 sequences. (Running on oeis4.)