|
|
A034855
|
|
Triangle read by rows giving number of rooted labeled trees with n >= 2 nodes and height d >= 1.
|
|
9
|
|
|
2, 3, 6, 4, 36, 24, 5, 200, 300, 120, 6, 1170, 3360, 2520, 720, 7, 7392, 38850, 43680, 22680, 5040, 8, 50568, 475776, 757680, 551040, 221760, 40320, 9, 372528, 6231960, 13747104, 12836880, 7136640, 2358720, 362880, 10, 2936070, 87530400, 264181680
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
2,1
|
|
LINKS
|
|
|
FORMULA
|
Riordan reference gives recurrence.
|
|
EXAMPLE
|
2;
3, 6;
4, 36, 24;
5, 200, 300, 120;
6, 1170, 3360, 2520, 720;
7, 7392, 38850, 43680, 22680, 5040;
|
|
MAPLE
|
gf:= proc(k) gf(k):= `if`(k=0, x, x*exp(gf(k-1))) end:
A:= proc(n, k) A(n, k):= n!*coeff(series(gf(k), x, n+1), x, n) end:
T:= (n, d)-> A(n, d) -A(n, d-1):
|
|
MATHEMATICA
|
gf[k_] := gf[k] = If[k == 0, x, x*E^gf[k - 1]]; a[n_, k_] := n!*Coefficient[ Series[gf[k], {x, 0, n + 1}], x, n]; t[n_, d_] := a[n, d] - a[n, d - 1]; Table[t[n, d], {n, 2, 12}, {d, 1, n - 1}] // Flatten (* Jean-François Alcover, Jan 15 2013, translated from Alois P. Heinz's Maple program *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
EXTENSIONS
|
More terms from Pab Ter (pabrlos(AT)yahoo.com), May 27 2004
|
|
STATUS
|
approved
|
|
|
|