A340679 If n is a power of prime then a(n) = 1, otherwise a(n) = product of the distinct prime factors of n.

1, 1, 1, 1, 1, 6, 1, 1, 1, 10, 1, 6, 1, 14, 15, 1, 1, 6, 1, 10, 21, 22, 1, 6, 1, 26, 1, 14, 1, 30, 1, 1, 33, 34, 35, 6, 1, 38, 39, 10, 1, 42, 1, 22, 15, 46, 1, 6, 1, 10, 51, 26, 1, 6, 55, 14, 57, 58, 1, 30, 1, 62, 21, 1, 65, 66, 1, 34, 69, 70, 1, 6, 1, 74, 15, 38, 77, 78, 1, 10, 1, 82, 1, 42, 85, 86, 87, 22, 1, 30, 91, 46

Offset: 1

Author

Antti Karttunen, Feb 01 2021

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384
• Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537

Crossrefs

Cf. A000961 (positions of ones), A007947, A010055, A014963.

Cf. also A048671, A322591.

Programs

Mathematica

Table[If[PrimePowerQ[n],1,Times@@FactorInteger[n][[All,1]]],{n,100}] (* Harvey P. Dale, May 23 2021 *)

PARI

A340679(n) = if(isprimepower(n),1,factorback(factorint(n)[, 1]));

Formula

If A010055(n) == 1 [when n is a power of prime], a(n) = 1, otherwise a(n) = A007947(n).

a(n) = A007947(n) / A014963(n).