A356933 Number of multisets of multisets, each of odd size, whose multiset union is a size-n multiset covering an initial interval.

1, 1, 2, 8, 28, 108, 524, 2608, 14176, 86576, 550672, 3782496, 27843880, 214071392, 1751823600, 15041687664, 134843207240, 1269731540864, 12427331494304, 126619822952928, 1341762163389920, 14712726577081248, 167209881188545344, 1963715680476759040, 23794190474350155856

Offset

0,3

Links

Andrew Howroyd, Table of n, a(n) for n = 0..500

Gus Wiseman, Counting and ranking classes of multiset partitions related to gapless multisets

Example

The a(4) = 28 multiset partitions:
  {1}{111}      {1}{112}      {1}{123}      {1}{234}
  {1}{1}{1}{1}  {1}{122}      {1}{223}      {2}{134}
                {1}{222}      {1}{233}      {3}{124}
                {2}{111}      {2}{113}      {4}{123}
                {2}{112}      {2}{123}      {1}{2}{3}{4}
                {2}{122}      {2}{133}
                {1}{1}{1}{2}  {3}{112}
                {1}{1}{2}{2}  {3}{122}
                {1}{2}{2}{2}  {3}{123}
                              {1}{1}{2}{3}
                              {1}{2}{2}{3}
                              {1}{2}{3}{3}

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]]]];
allnorm[n_]:=If[n<=0, {{}}, Function[s, Array[Count[s, y_/; y<=#]+1&, n]]/@Subsets[Range[n-1]+1]];
Table[Length[Select[Join@@mps/@allnorm[n], OddQ[Times@@Length/@#]&]], {n, 0, 5}]

Prog

(PARI)
EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}
R(n, k) = {EulerT(vector(n, j, if(j%2 == 1, binomial(j+k-1, j))))}
seq(n) = {concat([1], sum(k=1, n, R(n, k)*sum(r=k, n, binomial(r, k)*(-1)^(r-k)) ))} \\ Andrew Howroyd, Jan 01 2023

Crossrefs

A000041 counts integer partitions, strict A000009.

A000670 counts patterns, ranked by A333217, necklace A019536.

A011782 counts multisets covering an initial interval.

Cf. A055887, A063834, A072233, A270995, A304969, A349050, A349055.

Odd-size multisets are counted by A000302, A027193, A058695, ranked by A026424.

Other conditions: A034691, A116540, A255906, A356937, A356942.

Other types: A050330, A356932, A356934, A356935.

Sequence in context: A292668 A122447 A150715 * A026528 A150716 A151299

Adjacent sequences: A356930 A356931 A356932 * A356934 A356935 A356936

Keyword

nonn

Author

Gus Wiseman, Sep 08 2022

Extensions

Terms a(9) and beyond from Andrew Howroyd, Jan 01 2023

Status

approved