A327532 - OEIS

A327532

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

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, 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, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1

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OFFSET

COMMENTS

First differs from A327515 at index 225.

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.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

Gus Wiseman, Sequences counting and encoding certain classes of multisets

Index entries for characteristic functions.

Index entries for sequences related to prime indices in the factorization of n.

MATHEMATICA

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

PROG

(PARI) A327532(n) = { my(f=factor(n)); (1==gcd(apply(x->primepi(x), f[, 1]))); }; \\ Antti Karttunen, Jan 28 2025, after "isok" function in A289509 by Michel Marcus, Jul 19 2017

CROSSREFS

See link for additional cross-references.

Positions of 0's are A318978.

Positions of 1's are A289509.

Cf. A112798, A281116, A289509, A318721, A327515.

Sequence in context: A131734 A134452 A327515 * A073445 A285589 A179081

Adjacent sequences: A327529 A327530 A327531 * A327533 A327534 A327535

KEYWORD

nonn

AUTHOR

Gus Wiseman, Sep 17 2019

EXTENSIONS

More terms from Antti Karttunen, Jan 28 2025

STATUS

approved