A071213 - OEIS

A071213

Number of labeled planar trees with n nodes such that the root is smaller than all its children.

1, 4, 34, 436, 7428, 157368, 3980688, 116949600, 3911421600, 146673662400, 6093249563520, 277729608280320, 13778539159795200, 739059210587980800, 42615627311477606400, 2628646012982829772800, 172704619437756321484800

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,2

LINKS

Table of n, a(n) for n=2..18.

C. Chauve, S. Dulucq and O. Guibert, Enumeration of some labeled trees, research report RR-1226-99, LaBRI, Bordeaux I University, 1999.

FORMULA

E.g.f.: F(C(x))+x*[F(C(x))]', where C(x)/x is g.f. of Catalan numbers (A000108), F(x)=1+log(1-x)/x-log(1-x). - Vladimir Kruchinin, Mar 23 2016

MAPLE

n -> 2 * sum((n-1) * (n-2+k)! / (k! * (n-1-k)), k=0 .. n-2) - ((2*n-3)! / (n-2)!);

PROG

(Maxima)

C(x):=(1-sqrt(1-4*x))/(2);

F(x):=1+log(1-x)/x-log(1-x);

makelist(n!*coeff(taylor(F(C(x))+x*diff(F(C(x)), x), x, 0, 15), x, n), n, 1, 15); /*Vladimir Kruchinin, Mar 23 2016 */

CROSSREFS

Cf. A000108, A000312, A033184.

Sequence in context: A309170 A338163 A052630 * A052629 A151919 A277637

Adjacent sequences: A071210 A071211 A071212 * A071214 A071215 A071216

KEYWORD

easy,nonn

AUTHOR

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

STATUS

approved