A055304 Number of labeled rooted trees with n nodes and 3 leaves.

4, 140, 3000, 54600, 940800, 16087680, 279417600, 4989600000, 92207808000, 1769511744000, 35321737651200, 733823266176000, 15866448998400000, 356873052856320000, 8344427063132160000, 202660737281114112000

Offset

4,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 4..200

Index entries for sequences related to rooted trees

Formula

a(n) = (n!/3!)*Stirling2(n-1, n-3). - Vladeta Jovovic, Jan 28 2004

a(n) = n! * (n-3)*(n-2)*(n-1)*(3*n-8)/144. - Vaclav Kotesovec, Jul 25 2014

E.g.f.: x^4*(2*x+1)/(6*(1-x)^5). - Robert Israel, Jul 25 2014

Maple

seq(n!*(n-3)*(n-2)*(n-1)*(3*n-8)/144, n=4..100); # Robert Israel, Jul 25 2014

Mathematica

Table[n! * (n-3)*(n-2)*(n-1)*(3*n-8)/144, {n, 4, 20}] (* Vaclav Kotesovec, Jul 25 2014 *)

Prog

(Magma) [Factorial(n)*(n-3)*(n-2)*(n-1)*(3*n-8)/144 : n in [4..25]]; // Vincenzo Librandi, Jul 25 2014

Crossrefs

Column 3 of A055302.

Sequence in context: A340838 A291450 A093981 * A270065 A002917 A235536

Adjacent sequences: A055301 A055302 A055303 * A055305 A055306 A055307

Keyword

nonn

Author

Christian G. Bower, May 11 2000

Status

approved