cp's OEIS Frontend

A003448 Number of nonequivalent dissections of an n-gon into n-4 polygons by nonintersecting diagonals rooted at a cell up to rotation and reflection.

%I A003448 M2993 #22 Jan 19 2021 11:48:00
%S A003448 1,3,15,81,422,2124,10223,47813,218130,977354,4315130,18833538,
%T A003448 81424236,349303352,1488748719,6310303727,26621551418,111854042306,
%U A003448 468309841090,1954642186302,8136002036672,33782928166668,139971138117190,578803145957026
%N A003448 Number of nonequivalent dissections of an n-gon into n-4 polygons by nonintersecting diagonals rooted at a cell up to rotation and reflection.
%C A003448 Number of dissections of regular n-gon into n-4 polygons with reflection and rooted at a cell.- _Sean A. Irvine_, May 13 2015
%C A003448 The dissection will always be composed of either 1 pentagon and n-5 triangles or 2 quadrilaterals and n-6 triangles. - _Andrew Howroyd_, Nov 24 2017
%D A003448 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A003448 Andrew Howroyd, <a href="/A003448/b003448.txt">Table of n, a(n) for n = 5..200</a>
%H A003448 P. Lisonek, <a href="http://dx.doi.org/10.1006/jsco.1995.1066">Closed forms for the number of polygon dissections</a>, Journal of Symbolic Computation 20 (1995), 595-601.
%H A003448 Ronald C. Read, <a href="http://dx.doi.org/10.1007/BF03031688">On general dissections of a polygon</a>, Aequat. math. 18 (1978) 370-388.
%o A003448 (PARI) \\ See A003447 for DissectionsModDihedralRooted()
%o A003448 my(v=DissectionsModDihedralRooted(apply(i->if(i>=3&&i<=5,y^(i-3)+O(y^3)),[1..30]))); apply(p->polcoeff(p,2), v[5..#v]) \\ _Andrew Howroyd_, Nov 24 2017
%Y A003448 Cf. A003447.
%K A003448 nonn
%O A003448 5,2
%A A003448 _N. J. A. Sloane_
%E A003448 More terms from _Sean A. Irvine_, May 13 2015
%E A003448 Name clarified by _Andrew Howroyd_, Nov 24 2017