login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A055304 Number of labeled rooted trees with n nodes and 3 leaves. 1
4, 140, 3000, 54600, 940800, 16087680, 279417600, 4989600000, 92207808000, 1769511744000, 35321737651200, 733823266176000, 15866448998400000, 356873052856320000, 8344427063132160000, 202660737281114112000 (list; graph; refs; listen; history; text; internal format)
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: A221675 A291450 A093981 * A270065 A002917 A235536

Adjacent sequences:  A055301 A055302 A055303 * A055305 A055306 A055307

KEYWORD

nonn

AUTHOR

Christian G. Bower, May 11 2000

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 15 11:43 EST 2019. Contains 329999 sequences. (Running on oeis4.)