A055316 Number of labeled trees with n nodes and 4 leaves.

5, 210, 5250, 109200, 2116800, 40219200, 768398400, 14968800000, 299675376000, 6193291104000, 132456516192000, 2935293064704000, 67432408243200000, 1605928737853440000, 39636028549877760000, 1013303686405570560000, 26816358272375992320000, 734112975329750016000000

Offset: 5

Author

Christian G. Bower, May 11 2000

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 5..200
• Index entries for sequences related to trees

Crossrefs

Column 4 of A055314.

Programs

Magma

[Factorial(n)*(n-4)*(n-3)*(n-2)*(3*n-11)/576: n in [5..25]]; // Vincenzo Librandi, Jul 25 2014

Mathematica

Table[n! * (n-4)*(n-3)*(n-2)*(3*n-11)/576,{n,5,20}] (* Vaclav Kotesovec, Jul 25 2014 *)

Formula

a(n) = (n!/4!)*Stirling2(n-2, n-4). - Vladeta Jovovic, Jan 28 2004

a(n) = n! * (n-4)*(n-3)*(n-2)*(3*n-11)/576. - Vaclav Kotesovec, Jul 25 2014