A004304 Number of nonseparable planar tree-rooted maps with n edges.

1, 2, 2, 6, 28, 160, 1036, 7294, 54548, 426960, 3463304, 28910816, 247104976, 2154192248, 19097610480, 171769942086, 1564484503044, 14407366963440, 133978878618904, 1256799271555872, 11881860129979440

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

References

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

Links

• Gheorghe Coserea, Table of n, a(n) for n = 0..200
• Dov Tamari, Monoïdes préordonnés et chaînes de Malcev, Bulletin de la Société Mathématique de France, Volume 82 (1954), 53-96. See end of Appendix II.
• T. R. S. Walsh, A. B. Lehman, Counting rooted maps by genus. III: Nonseparable maps, J. Combinatorial Theory Ser. B 18 (1975), 222-259. See Table IVc.

Crossrefs

Cf. A000264.

Cf. A005568, A168450, A168451, A168452. - Paul D. Hanna, Nov 26 2009

Programs

Maple

A004304 := proc(n) local N,x,ode ; Order := n+1 ; ode := x^2*diff(N(x),x,x)*(N(x)^3-16*x*N(x)) ; ode := ode + (x*diff(N(x),x))^3*(16-6*N(x)) ; ode := ode + (x*diff(N(x),x))^2*(12*N(x)^2-16*x-24*N(x)) ; ode := ode + x*diff(N(x),x)*(-8*N(x)^3+24*x*N(x)+12*N(x)^2) ; ode := ode + 2*N(x)^2*(N(x)^2-N(x)-6*x) ; dsolve({ode=0,N(0)=1,D(N)(0)=2},N(x),type=series) ; convert(%,polynom) ; rhs(%) ; RETURN( coeftayl(%,x=0,n)) ; end; for n from 0 to 20 do printf("%d,",A004304(n)) ; od ; # R. J. Mathar, Aug 18 2006

Mathematica

m = 22;
F[x_] = Sum[2 (2n+1) Binomial[2n, n]^2 x^n/((n+2)(n+1)^2), {n, 0, m}];
A[x_] = (x/InverseSeries[x F[x]^2 + O[x]^m, x])^(1/2);
CoefficientList[A[x], x] (* Jean-François Alcover, Mar 28 2020 *)

PARI

{a(n)=local(C_2=vector(n+1,m,(binomial(2*m-2,m-1)/m)*(binomial(2*m,m)/(m+1))));polcoeff((x/serreverse(x*Ser(C_2)^2))^(1/2),n)} \\ Paul D. Hanna, Nov 26 2009

PARI

seq(N) = {
  my(c(n)=binomial(2*n,n)/(n+1), s=Ser(apply(n->c(n)*c(n+1), [0..N])));
  Vec(subst(s, 'x, serreverse('x*s^2)));
};
seq(20)
\\ test: y=Ser(seq(200)); 0 == x^2*y''*(y^3 - 16*x*y) + (x*y')^3*(16-6*y) + (x*y')^2*(12*y^2-16*x-24*y) + x*y'*(-8*y^3 + 24*x*y + 12*y^2) + 2*y^2*(y^2-y-6*x)
\\ Gheorghe Coserea, Jun 13 2018

Formula

From Paul D. Hanna, Nov 26 2009: (Start)

G.f.: A(x) = [x/Series_Reversion(x*F(x)^2)]^(1/2) where F(x) = g.f. of A005568, where A005568(n) is the product of two successive Catalan numbers C(n)*C(n+1).

G.f.: A(x) = F(x/A(x)^2) where A(x*F(x)^2) = F(x) where F(x) = g.f. of A005568.

G.f.: A(x) = G(x/A(x)) where A(x*G(x)) = G(x) where F(x) = g.f. of A168450.

G.f.: A(x) = x/Series_Reversion(x*G(x)) where G(x) = g.f. of A168450.

Self-convolution yields A168451.

(End)

Extensions

More terms from R. J. Mathar, Aug 18 2006