A320171 Number of series-reduced rooted identity trees whose leaves are integer partitions whose multiset union is an integer partition of n.

1, 2, 5, 11, 29, 82, 247, 782, 2579, 8702, 29975, 104818, 371111, 1327307, 4788687, 17404838, 63669763, 234237605, 866090021, 3216738344, 11995470691, 44894977263, 168582174353, 634939697164, 2398004674911, 9079614633247, 34458722286825, 131059771522401

Offset

1,2

Comments

A rooted tree is series-reduced if every non-leaf node has at least two branches.

In an identity tree, all branches directly under any given node are different.

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

Example

The a(1) = 1 through a(4) = 11 rooted identity trees:
  (1)  (2)   (3)        (4)
       (11)  (21)       (22)
             (111)      (31)
             ((1)(2))   (211)
             ((1)(11))  (1111)
                        ((1)(3))
                        ((1)(21))
                        ((2)(11))
                        ((1)(111))
                        ((1)((1)(2)))
                        ((1)((1)(11)))

Mathematica

sps[{}]:={{}}; sps[set:{i_, ___}]:=Join@@Function[s, Prepend[#, s]&/@sps[Complement[set, s]]]/@Cases[Subsets[set], {i, ___}];
mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
gig[m_]:=Prepend[Join@@Table[Union[Sort/@Select[Sort/@Tuples[gig/@mtn], UnsameQ@@#&]], {mtn, Select[mps[m], Length[#]>1&]}], m];
Table[Sum[Length[gig[y]], {y, IntegerPartitions[n]}], {n, 8}]

Prog

(PARI) WeighT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, (-1)^(n-1)/n))))-1, -#v)}
seq(n)={my(v=vector(n)); for(n=1, n, v[n]=numbpart(n) + WeighT(v[1..n])[n]); v} \\ Andrew Howroyd, Oct 25 2018

Crossrefs

Cf. A000081, A000311, A000669, A001678, A005804, A141268, A292504, A300660, A319312, A320172, A320177, A320178.

Sequence in context: A192785 A334578 A360810 * A014211 A160911 A092764

Adjacent sequences: A320168 A320169 A320170 * A320172 A320173 A320174

Keyword

nonn

Author

Gus Wiseman, Oct 07 2018

Extensions

Terms a(12) and beyond from Andrew Howroyd, Oct 25 2018

Status

approved