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A290722 Number of dissections of a 2n-gon into polygons with even number of sides counted up to rotations and reflections. 3
1, 2, 4, 13, 48, 238, 1325, 8297, 54519, 373363, 2621872, 18797682, 136969519, 1011903735, 7564219361, 57129086391, 435394899361, 3345082819597, 25885718422329, 201619294539406, 1579629974876090, 12442262963919863, 98483477967355109, 783017782731507416 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 2..200

Evgeniy Krasko, Alexander Omelchenko, Brown's Theorem and its Application for Enumeration of Dissections and Planar Trees, The Electronic Journal of Combinatorics, 22 (2015), #P1.17.

EXAMPLE

For a(4) = 4 the dissections of an octagon are: two dissections into 3 quadrangles; a dissection into one hexagon and one quadrangle; a dissection into one octagon.

PROG

(PARI) \\ See A295419 for DissectionsModDihedral().

select(v->v>0, DissectionsModDihedral(apply(v->v%2==0, [1..50]))) \\ Andrew Howroyd, Nov 22 2017

CROSSREFS

Cf. A003168 (counted distinctly).

Cf. A001004, A290816, A295419.

Sequence in context: A005164 A246494 A268951 * A058134 A246012 A069730

Adjacent sequences:  A290719 A290720 A290721 * A290723 A290724 A290725

KEYWORD

nonn

AUTHOR

Evgeniy Krasko, Sep 03 2017

EXTENSIONS

Terms a(8) and beyond from Andrew Howroyd, Nov 22 2017

STATUS

approved

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Last modified October 21 03:24 EDT 2019. Contains 328291 sequences. (Running on oeis4.)