cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A322454 Number of multiset partitions with no constant parts of a multiset whose multiplicities are the prime indices of n.

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 0, 1, 2, 1, 0, 2, 0, 1, 2, 4, 0, 4, 0, 3, 3, 1, 0, 7, 4, 1, 9, 4, 0, 7, 0, 11, 3, 1, 5, 15, 0, 1, 4, 11
Offset: 1

Views

Author

Gus Wiseman, Dec 09 2018

Keywords

Comments

This multiset (row n of A305936) is generally not the same as the multiset of prime indices of n. For example, the prime indices of 12 are {1,1,2}, while a multiset whose multiplicities are {1,1,2} is {1,1,2,3}.

Examples

			The a(30) = 7 multiset partitions:
    {{1,1,1,2,2,3}}
   {{1,2},{1,1,2,3}}
   {{1,3},{1,1,2,2}}
   {{2,3},{1,1,1,2}}
   {{1,1,2},{1,2,3}}
   {{1,1,3},{1,2,2}}
  {{1,2},{1,2},{1,3}}
		

Crossrefs

Programs

  • Mathematica
    nrmptn[n_]:=Join@@MapIndexed[Table[#2[[1]],{#1}]&,If[n==1,{},Flatten[Cases[FactorInteger[n]//Reverse,{p_,k_}:>Table[PrimePi[p],{k}]]]]];
    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]]]];
    Table[Length[Select[mps[nrmptn[n]],Min@@Length/@Union/@#>1&]],{n,20}]