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A330655 Number of balanced reduced multisystems of weight n whose atoms cover an initial interval of positive integers. 11
1, 1, 2, 12, 138, 2652, 78106, 3256404, 182463296, 13219108288, 1202200963522, 134070195402644, 17989233145940910, 2858771262108762492, 530972857546678902490, 113965195745030648131036, 27991663753030583516229824, 7800669355870672032684666900, 2448021231611414334414904013956 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A balanced reduced multisystem is either a finite multiset, or a multiset partition with at least two parts, not all of which are singletons, of a balanced reduced multisystem. The weight of an atom is 1, while the weight of a multiset is the sum of weights of its elements.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..200

EXAMPLE

The a(0) = 1 through a(3) = 12 multisystems:

  {}  {1}  {1,1}  {1,1,1}

           {1,2}  {1,1,2}

                  {1,2,2}

                  {1,2,3}

                  {{1},{1,1}}

                  {{1},{1,2}}

                  {{1},{2,2}}

                  {{1},{2,3}}

                  {{2},{1,1}}

                  {{2},{1,2}}

                  {{2},{1,3}}

                  {{3},{1,2}}

MATHEMATICA

allnorm[n_]:=If[n<=0, {{}}, Function[s, Array[Count[s, y_/; y<=#]+1&, n]]/@Subsets[Range[n-1]+1]];

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]]]];

totm[m_]:=Prepend[Join@@Table[totm[p], {p, Select[mps[m], 1<Length[#]<Length[m]&]}], m];

Table[Sum[Length[totm[m]], {m, allnorm[n]}], {n, 0, 5}]

PROG

(PARI)

EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}

R(n, k)={my(v=vector(n), u=vector(n)); v[1]=k; for(n=1, #v, u += v*sum(j=n, #v, (-1)^(j-n)*binomial(j-1, n-1)); v=EulerT(v)); u}

seq(n)={concat([1], sum(k=1, n, R(n, k)*sum(r=k, n, binomial(r, k)*(-1)^(r-k))))} \\ Andrew Howroyd, Dec 30 2019

CROSSREFS

Row sums of A330776.

The unlabeled version is A330474.

The strongly normal case is A330475.

The tree version is A330654.

The maximum-depth case is A330676.

The case where the atoms are all different is A005121.

The case where the atoms are all equal is A318813.

Multiset partitions of normal multisets are A255906.

Series-reduced rooted trees with normal leaves are A316651.

Cf. A000311, A000669, A001678, A213427, A318812, A330675, A330679.

Sequence in context: A297078 A185522 A119819 * A093543 A287885 A091144

Adjacent sequences:  A330652 A330653 A330654 * A330656 A330657 A330658

KEYWORD

nonn

AUTHOR

Gus Wiseman, Dec 27 2019

EXTENSIONS

Terms a(7) and beyond from Andrew Howroyd, Dec 30 2019

STATUS

approved

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Last modified July 27 23:16 EDT 2021. Contains 346316 sequences. (Running on oeis4.)