cp's OEIS Frontend

A368603 Products of odd primes of squarefree index. MM-numbers of set multipartitions.

%I A368603 #5 Jan 08 2024 14:30:42
%S A368603 1,3,5,9,11,13,15,17,25,27,29,31,33,39,41,43,45,47,51,55,59,65,67,73,
%T A368603 75,79,81,83,85,87,93,99,101,109,113,117,121,123,125,127,129,135,137,
%U A368603 139,141,143,145,149,153,155,157,163,165,167,169,177,179,181,187
%N A368603 Products of odd primes of squarefree index. MM-numbers of set multipartitions.
%C A368603 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798. The multiset of multisets with MM-number n is formed by taking the multiset of prime indices of each part of the multiset of prime indices of n. For example, the prime indices of 78 are {1,2,6}, so the multiset of multisets with MM-number 78 is {{},{1},{1,2}}.
%C A368603 A set multipartition is a finite multiset of finite nonempty sets.
%e A368603 The terms together with the corresponding set multipartitions begin:
%e A368603    1: {}
%e A368603    3: {{1}}
%e A368603    5: {{2}}
%e A368603    9: {{1},{1}}
%e A368603   11: {{3}}
%e A368603   13: {{1,2}}
%e A368603   15: {{1},{2}}
%e A368603   17: {{4}}
%e A368603   25: {{2},{2}}
%e A368603   27: {{1},{1},{1}}
%e A368603   29: {{1,3}}
%e A368603   31: {{5}}
%e A368603   33: {{1},{3}}
%e A368603   39: {{1},{1,2}}
%e A368603   41: {{6}}
%e A368603   43: {{1,4}}
%e A368603   45: {{1},{1},{2}}
%t A368603 prix[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
%t A368603 Select[Range[100],OddQ[#]&&And@@SquareFreeQ/@prix[#]&]
%Y A368603 Odd case of A302478.
%Y A368603 Products of odd terms of A302491.
%Y A368603 A049311 counts non-isomorphic set multipartitions, strict A283877.
%Y A368603 A050320 counts set multipartitions of prime indices.
%Y A368603 A056239 adds up prime indices, row sums of A112798.
%Y A368603 A089259 counts set multipartitions of integer partitions.
%Y A368603 A116540 counts set multipartitions covering an initial interval by weight.
%Y A368603 A368533 lists numbers with squarefree binary indices.
%Y A368603 Cf. A000040, A000720, A001222, A005117, A006450, A076610, A270995, A296119, A302242, A302590, A339113.
%K A368603 nonn
%O A368603 1,2
%A A368603 _Gus Wiseman_, Jan 08 2024