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A003452 Number of nonequivalent dissections of an n-gon into 3 polygons by nonintersecting diagonals rooted at a cell up to rotation and reflection.
(Formerly M1742)
3
2, 7, 15, 28, 45, 69, 98, 136, 180, 235, 297, 372, 455, 553, 660, 784, 918, 1071, 1235, 1420, 1617, 1837, 2070, 2328, 2600, 2899, 3213, 3556, 3915, 4305, 4712, 5152, 5610, 6103, 6615, 7164, 7733, 8341, 8970, 9640, 10332, 11067, 11825, 12628 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,1

COMMENTS

Number of dissections of regular n-gon into 3 polygons with reflection and rooted at a cell. - Sean A. Irvine, May 14 2015

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Andrew Howroyd, Table of n, a(n) for n = 5..500

P. Lisonek, Closed forms for the number of polygon dissections, Journal of Symbolic Computation 20 (1995), 595-601.

C. R. Read, On general dissections of a polygon, Aequat. math. 18 (1978) 370-388.

PROG

(PARI) \\ See A003447 for DissectionsModDihedralRooted()

{ my(v=DissectionsModDihedralRooted(apply(i->y+O(y^4), [1..40]))); apply(p->polcoeff(p, 3), v[5..#v]) } \\ Andrew Howroyd, Nov 24 2017

CROSSREFS

Cf. A003447.

Sequence in context: A113422 A061802 A263603 * A000148 A147672 A246790

Adjacent sequences:  A003449 A003450 A003451 * A003453 A003454 A003455

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Sean A. Irvine, May 14 2015

Name clarified by Andrew Howroyd, Nov 24 2017

STATUS

approved

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Last modified March 21 18:59 EDT 2019. Contains 321382 sequences. (Running on oeis4.)