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A303839 Number of noncrossing path sets on n nodes up to rotation and reflection with each path having at least two nodes. 6
1, 0, 1, 1, 3, 5, 17, 40, 138, 430, 1546, 5478, 20525, 77310, 298301, 1161692, 4583525, 18239037, 73221198, 296046399, 1205038270, 4933969005, 20311807087, 84029440358, 349201537324, 1457205298510, 6104204225832, 25661191956781, 108231773165825 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..200

EXAMPLE

Case n=4: There are 3 possibilities:

.

   o---o   o   o   o---o

           |   |     /

   o---o   o---o   o---o

.

PROG

(PARI) \\ See A303731 for NCPathSetsModDihedral

Vec(NCPathSetsModDihedral(vector(30, k, k>1)))

CROSSREFS

Cf. A303730, A303731, A303835, A303844.

Sequence in context: A148519 A148520 A148521 * A148522 A141160 A113275

Adjacent sequences:  A303836 A303837 A303838 * A303840 A303841 A303842

KEYWORD

nonn

AUTHOR

Andrew Howroyd, May 01 2018

STATUS

approved

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Last modified May 21 15:02 EDT 2019. Contains 323443 sequences. (Running on oeis4.)