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A220898 Number of primitive maps on n edges. 1
2, 1, 1, 3, 9, 32, 122, 494, 2088, 9130, 41018, 188420, 881718, 4191343, 20194345, 98442879, 484826387, 2409437854, 12070883798, 60910296202, 309356790766, 1580443960788, 8117428327384, 41896435989770, 217209722907220, 1130759644970931, 5908990116854607, 30987487474146447, 163034985804927311 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..28.

S. Kitaev, P. Salimov, C. Severs and H. Ulfarsson, Restricted non-separable planar maps and some pattern avoiding permutations, 2012.

S. Kitaev, P. Salimov, C. Severs and H. Ulfarsson, Restricted non-separable planar maps and some pattern avoiding permutations, Discrete Applied Mathematics, Volume 161, Issues 16-17, November 2013, Pages 2514-2526.

FORMULA

G.f.: A(x/(1+x)), where A(x) is g.f. for A000139.

Conjecture: 2*(n+1)*(2*n+1)*a(n) +(-15*n^2+19*n-8)*a(n-1) -2*(21*n-22)*(n-2)*a(n-2) -23*(n-2)*(n-3)*a(n-3)=0. - R. J. Mathar, May 30 2014

MATHEMATICA

A[x_] = (2/(3x)) (HypergeometricPFQ[{-2/3, -1/3}, {1/2}, (27/4) x] - 1);

A[x/(1+x)] + O[x]^29 // CoefficientList[#, x]& (* Jean-Fran├žois Alcover, Aug 29 2019 *)

CROSSREFS

Sequence in context: A219206 A077385 A337219 * A336163 A066013 A212261

Adjacent sequences:  A220895 A220896 A220897 * A220899 A220900 A220901

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jan 01 2013

STATUS

approved

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Last modified October 21 17:37 EDT 2021. Contains 348155 sequences. (Running on oeis4.)