A248099 - OEIS

%I #15 Jan 10 2015 13:27:33

%S 1,4,216,2428912656,84539502447168140812774402430429967453919558368

%N Number of ordered trees with root degree n and having strictly thinning limbs. An ordered tree with strictly thinning limbs is such that if a node has k children, each of its children has less than k children.

%C The next term is too large to include (282 digits).

%C First differences of A110387.

%F a(1)=1; a(n) = (1 + a(1) + ... + a(n-1))^n for n>=2.

%F a(1)=1; a(n) = (a(n-1)^{1/(n-1)} + a(n-1))^n for n>=2.

%F For the g.f. F[n](z) of the ordered trees with root degree n and having strictly thinning limbs, where z marks number of vertices, we  have F[1](z) = z^2 and F[n] = z*(F[n-1] + (F[n-1]/z)^{1/(n-1)})^n for n>=2.

%e a(2)=4; indeed, we have /\ and the 3 trees obtained by hanging | to either of the leaves of /\ or to both of them.

%p a[1] := 1: for n from 2 to 6 do a[n] := simplify((a[n-1]^(1/(n-1))+a[n-1])^n) end do: seq(a[n], n = 1 .. 6);

%Y Cf. A110387.

%K nonn

%O 1,2

%A _Emeric Deutsch_, Jan 09 2015