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A330762
Triangle read by rows: T(n,k) is the number of series-reduced rooted trees whose leaves are multisets of colors with a total of n elements using exactly k colors.
3
1, 2, 2, 4, 12, 8, 11, 67, 114, 58, 30, 376, 1230, 1496, 612, 96, 2174, 12038, 26156, 24570, 8374, 308, 12792, 113028, 389968, 630300, 481284, 140408, 1052, 76972, 1043355, 5363331, 13259870, 17008218, 10930150, 2785906, 3648, 471260, 9574934, 70524256, 250201560, 479284952, 508811114, 282141552, 63830764
OFFSET
1,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..1275 (first 50 rows)
EXAMPLE
Triangle begins:
1;
2, 2;
4, 12, 8;
11, 67, 114, 58;
30, 376, 1230, 1496, 612;
96, 2174, 12038, 26156, 24570, 8374;
308, 12792, 113028, 389968, 630300, 481284, 140408;
1052, 76972, 1043355, 5363331, 13259870, 17008218, 10930150, 2785906;
...
The T(3,2) = 12 trees are: (122), (112), ((1)(22)), ((1)(12)), ((2)(12)), ((2)(11)), ((1)(2)(2)), ((1)(1)(2)), ((1)((2)(2))), ((1)((1)(2))), ((2)((1)(2))), ((2)((1)(1))).
PROG
(PARI)
EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}
R(n, k)={my(v=[]); for(n=1, n, v=concat(v, EulerT(concat(v, [binomial(n+k-1, k-1)]))[n])); v}
M(n)={my(v=vector(n, k, R(n, k)~)); Mat(vector(n, k, sum(i=1, k, (-1)^(k-i)*binomial(k, i)*v[i])))}
{ my(T=M(10)); for(n=1, #T~, print(T[n, 1..n])) }
CROSSREFS
Column 1 is A141268.
Main diagonal is A005804.
Row sums are A330469.
Cf. A330763 (leaves are sets).
Sequence in context: A202795 A256890 A110476 * A059343 A285944 A112473
KEYWORD
nonn,tabl
AUTHOR
Andrew Howroyd, Dec 29 2019
STATUS
approved