A274081 Number of unrooted labeled trees on 3n+2 nodes with node degree either one or four.

1, 5, 560, 277200, 369969600, 1040623584000, 5318844410880000, 44743448895425280000, 577102758498249984000000, 10821132329283106871040000000, 283002122589833107696435200000000, 9986037506585076241055342592000000000, 462684151212030123561950840428953600000000

Offset: 0

Author

Marko Riedel, Jun 09 2016

Keywords

• nonn

Comments

There are no unrooted labeled trees on 3n or 3n+1 nodes with node degree either one or four.

Links

• Math.Stackexchange.com, Marko Riedel et al., Number of labeled trees

Crossrefs

Cf. A274056, A000272.

Programs

Maple

seq(binomial(3*n+2, n)*(3*n)!/(3!^n), n=0..16);

Mathematica

Table[Binomial[3*n+2, n]*(3*n)!/(3!)^n, {n,0,10}] (* G. C. Greubel, Jun 09 2016 *)