A274081 - OEIS

%I #9 Jun 10 2016 04:45:21

%S 1,5,560,277200,369969600,1040623584000,5318844410880000,

%T 44743448895425280000,577102758498249984000000,

%U 10821132329283106871040000000,283002122589833107696435200000000,9986037506585076241055342592000000000,462684151212030123561950840428953600000000

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

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

%H Math.Stackexchange.com, Marko Riedel et al., <a href="http://math.stackexchange.com/questions/1816933/">Number of labeled trees</a>

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

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

%Y Cf. A274056, A000272.

%K nonn

%O 0,2

%A _Marko Riedel_, Jun 09 2016