A291203 - OEIS

A291203

Number F(n,h,t) of forests of t labeled rooted trees with n vertices such that h is the maximum of 0 and the tree heights; triangle of triangles F(n,h,t), n>=0, h=0..n, t=0..n-h, read by layers, then by rows.

1, 0, 1, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0, 1, 0, 3, 6, 0, 6, 0, 0, 0, 0, 0, 1, 0, 4, 24, 12, 0, 36, 24, 0, 24, 0, 0, 0, 0, 0, 0, 1, 0, 5, 80, 90, 20, 0, 200, 300, 60, 0, 300, 120, 0, 120, 0, 0, 0, 0, 0, 0, 0, 1, 0, 6, 240, 540, 240, 30, 0, 1170, 3000, 1260, 120, 0, 3360, 2520, 360, 0, 2520, 720, 0, 720, 0

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OFFSET

0,9

COMMENTS

Positive elements in column t=1 give A034855.

Elements in rows h=0 give A023531.

Elements in rows h=1 give A059297.

Positive row sums per layer give A235595.

Positive column sums per layer give A061356.

LINKS

Alois P. Heinz, Layers n = 0..48, flattened

FORMULA

Sum_{i=0..n} F(n,i,n-i) = A243014(n) = 1 + A038154(n).

Sum_{d=0..n} Sum_{i=0..d} F(n,i,d-i) = A000272(n+1).

Sum_{h=0..n} Sum_{t=0..n-h} t * F(n,h,t) = A089946(n-1) for n>0.

Sum_{h=0..n} Sum_{t=0..n-h} (h+1) * F(n,h,t) = A234953(n+1) for n>0.

Sum_{h=0..n} Sum_{t=0..n-h} (h+1)*(n+1) * F(n,h,t) = A001854(n+1) for n>0.

Sum_{t=0..n-1} F(n,1,t) = A235596(n+1).

F(2n,n,n) = A126804(n) for n>0.

F(n,0,n) = 1 = A000012(n).

F(n,1,1) = n = A001477(n) for n>1.

F(n,n-1,1) = n! = A000142(n) for n>0.

F(n,1,n-1) = A002378(n-1) for n>0.

F(n,2,1) = A000551(n).

F(n,3,1) = A000552(n).

F(n,4,1) = A000553(n).

F(n,1,2) = A001788(n-1) for n>2.

F(n,0,0) = A000007(n).

EXAMPLE

n h\t: 0 1 2 3 4 5 : A235595 : A061356 : A000272

-----+-------------------+---------+------------------+--------

0 0 : 1 : : : 1

-----+-------------------+---------+------------------+--------

1 0 : 0 1 : 1 : . :

1 1 : 0 : : 1 : 1

-----+-------------------+---------+------------------+--------

2 0 : 0 0 1 : 1 : . . :

2 1 : 0 2 : 2 : . :

2 2 : 0 : : 2 1 : 3

-----+-------------------+---------+------------------+--------

3 0 : 0 0 0 1 : 1 : . . . :

3 1 : 0 3 6 : 9 : . . :

3 2 : 0 6 : 6 : . :

3 3 : 0 : : 9 6 1 : 16

-----+-------------------+---------+------------------+--------

4 0 : 0 0 0 0 1 : 1 : . . . . :

4 1 : 0 4 24 12 : 40 : . . . :

4 2 : 0 36 24 : 60 : . . :

4 3 : 0 24 : 24 : . :

4 4 : 0 : : 64 48 12 1 : 125

-----+-------------------+---------+------------------+--------

5 0 : 0 0 0 0 0 1 : 1 : . . . . . :

5 1 : 0 5 80 90 20 : 195 : . . . . :

5 2 : 0 200 300 60 : 560 : . . . :

5 3 : 0 300 120 : 420 : . . :

5 4 : 0 120 : 120 : . :

5 5 : 0 : : 625 500 150 20 1 : 1296

-----+-------------------+---------+------------------+--------

MAPLE

b:= proc(n, t, h) option remember; expand(`if`(n=0 or h=0, x^(t*n), add(

binomial(n-1, j-1)*j*x^t*b(j-1, 0, h-1)*b(n-j, t, h), j=1..n)))

end:

g:= (n, h)-> b(n, 1, h)-`if`(h=0, 0, b(n, 1, h-1)):

F:= (n, h, t)-> coeff(g(n, h), x, t):

seq(seq(seq(F(n, h, t), t=0..n-h), h=0..n), n=0..8);

MATHEMATICA

b[n_, t_, h_] := b[n, t, h] = Expand[If[n == 0 || h == 0, x^(t*n), Sum[

Binomial[n-1, j-1]*j*x^t*b[j-1, 0, h-1]*b[n-j, t, h], {j, 1, n}]]];

g[n_, h_] := b[n, 1, h] - If[h == 0, 0, b[n, 1, h - 1]];

F[n_, h_, t_] := Coefficient[g[n, h], x, t];

Table[Table[Table[F[n, h, t], {t, 0, n - h}], {h, 0, n}], {n, 0, 8}] // Flatten (* Jean-François Alcover, Mar 17 2022, after Alois P. Heinz *)

CROSSREFS

Cf. A000007, A000012, A000142, A000272, A000551, A001477, A001788, A001854, A002378, A023531, A034855, A038154, A059297, A061356, A089946, A126804, A234953, A235595, A235596, A243014, A291204, A291336, A291529.

Sequence in context: A227835 A281154 A245536 * A256852 A128616 A331902

Adjacent sequences: A291200 A291201 A291202 * A291204 A291205 A291206

KEYWORD

nonn,look,tabf

AUTHOR

Alois P. Heinz, Aug 20 2017

STATUS

approved