Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #7 Sep 23 2019 13:43:17
%S 1,1,3,1,5,1,7,1,9,1,11,1,13,1,1,1,17,1,19,1,21,1,23,1,25,1,27,1,29,1,
%T 31,1,1,1,1,1,37,1,39,1,41,1,43,1,1,1,47,1,49,1,1,1,53,1,1,1,57,1,59,
%U 1,61,1,63,1,65,1,67,1,1,1,71,1,73,1,1,1,1,1
%N a(n) = 1 if the prime indices of n are relatively prime, otherwise a(n) = n.
%C 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. Numbers whose prime indices are relatively prime are A289509. The maximum divisor of n that is 1 or whose prime indices are relatively prime is A327529(n).
%C Also the quotient of n over the maximum divisor of n that is 1 or whose prime indices are relatively prime.
%H Gus Wiseman, <a href="https://docs.google.com/document/d/e/2PACX-1vSX9dPMGJhxB8rOknCGvOs6PiyhupdWNpqLsnphdgU6MEVqFBnWugAXidDhwHeKqZe_YnUqYeGOXsOk/pub">Sequences counting and encoding certain classes of multisets</a>
%t Table[n/Max[Select[Divisors[n],#==1||GCD@@PrimePi/@First/@FactorInteger[#]==1&]],{n,100}]
%Y See link for additional cross-references.
%Y Cf. A000005, A112798, A281116, A289509.
%K nonn
%O 1,3
%A _Gus Wiseman_, Sep 17 2019