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Number T(n,k) of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals k; triangle T(n,k), n>=1, 0<=k<=n-1, read by rows.
11

%I #22 Sep 07 2018 21:12:11

%S 1,0,1,0,1,1,0,4,0,1,0,11,2,0,1,0,36,5,0,0,1,0,117,11,3,0,0,1,0,393,

%T 28,7,0,0,0,1,0,1339,78,8,4,0,0,0,1,0,4630,201,21,9,0,0,0,0,1,0,16193,

%U 532,55,10,5,0,0,0,0,1,0,57201,1441,121,11,11,0,0,0,0,0,1

%N Number T(n,k) of ordered unlabeled rooted trees with n nodes such that the minimal outdegree of inner nodes equals k; triangle T(n,k), n>=1, 0<=k<=n-1, read by rows.

%C T(1,0) = 1 by convention.

%H Alois P. Heinz, <a href="/A244530/b244530.txt">Rows n = 1..141, flattened</a>

%e T(5,1) = 11:

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%e Triangle T(n,k) begins:

%e 1;

%e 0, 1;

%e 0, 1, 1;

%e 0, 4, 0, 1;

%e 0, 11, 2, 0, 1;

%e 0, 36, 5, 0, 0, 1;

%e 0, 117, 11, 3, 0, 0, 1;

%e 0, 393, 28, 7, 0, 0, 0, 1;

%e 0, 1339, 78, 8, 4, 0, 0, 0, 1;

%e 0, 4630, 201, 21, 9, 0, 0, 0, 0, 1;

%e 0, 16193, 532, 55, 10, 5, 0, 0, 0, 0, 1;

%p b:= proc(n, t, k) option remember; `if`(n=0,

%p `if`(t in [0, k], 1, 0), `if`(t>n, 0, add(b(j-1, k$2)*

%p b(n-j, max(0, t-1), k), j=1..n)))

%p end:

%p T:= (n, k)-> b(n-1, k$2) -`if`(n=1 and k=0, 0, b(n-1, k+1$2)):

%p seq(seq(T(n, k), k=0..n-1), n=1..14);

%t b[n_, t_, k_] := b[n, t, k] = If[n == 0, If[t == 0 || t == k, 1, 0], If[t>n, 0, Sum[b[j-1, k, k]*b[n-j, Max[0, t-1], k], {j, 1, n}]]]; T[n_, k_] := b[n-1, k, k] - If[n == 1 && k == 0, 0, b[n-1, k+1, k+1]]; Table[Table[T[n, k], {k, 0, n-1}], {n, 1, 14}] // Flatten (* _Jean-François Alcover_, Jan 13 2015, translated from Maple *)

%Y Columns k=0-10 give: A063524, A106640(n-2), A244531, A244532, A244533, A244534, A244535, A244536, A244537, A244538, A244539.

%Y Row sums give A000108(n-1).

%Y Cf. A244454 (unordered unlabeled rooted trees).

%K nonn,tabl

%O 1,8

%A _Joerg Arndt_ and _Alois P. Heinz_, Jun 29 2014