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Indicator function for numbers whose prime indices are relatively prime (A289509).
0

%I #7 Sep 18 2019 04:57:34

%S 0,1,0,1,0,1,0,1,0,1,0,1,0,1,1,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,1,1,

%T 1,1,0,1,0,1,0,1,0,1,1,1,0,1,0,1,1,1,0,1,1,1,0,1,0,1,0,1,0,1,0,1,0,1,

%U 1,1,0,1,0,1,1,1,1,1,0,1,0,1,0,1,1,1,0

%N Indicator function for numbers whose prime indices are relatively prime (A289509).

%C First differs from A327515 at index 225.

%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. After 2, the first connected number (A305078) with relatively prime prime indices is 195.

%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[Boole[GCD@@PrimePi/@First/@FactorInteger[n]==1],{n,100}]

%Y See link for additional cross-references.

%Y Positions of 0's are A318978.

%Y Positions of 1's are A289509.

%Y Cf. A112798, A281116, A289509, A318721.

%K nonn

%O 1

%A _Gus Wiseman_, Sep 17 2019