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A058656 a(n) = gcd(n+1, phi(n)). 0
1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 3, 8, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 1, 2, 1, 12, 1, 2, 3, 8, 1, 2, 1, 2, 5, 2, 1, 2, 1, 2, 1, 4, 1, 2, 1, 8, 3, 2, 1, 2, 1, 2, 3, 4, 1, 6, 1, 2, 1, 2, 1, 2, 1, 2, 3, 4, 1, 6, 1, 2, 1, 2, 1, 2, 1, 2, 3, 8, 1, 2, 1, 4, 1, 2, 1, 24, 1, 2, 3, 20, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Compare sequences gcd(x, phi(n)), where x = n-1, n, or n+1.

LINKS

Table of n, a(n) for n=1..102.

EXAMPLE

For n = 12, 13, 14, 15:

n+1 = 13, 14, 15, 16;

phi(n) = 4, 12, 12, 8;

a(n) = gcd(13,4), gcd(14,12), gcd(15,12), gcd(16,8) = 1, 2, 3, 8, respectively.

MATHEMATICA

Table[GCD[n+1, EulerPhi[n]], {n, 110}] (* Harvey P. Dale, Nov 17 2011 *)

CROSSREFS

Cf. A000010, A009195, A058515.

Sequence in context: A161302 A161277 A160981 * A184221 A226898 A338653

Adjacent sequences:  A058653 A058654 A058655 * A058657 A058658 A058659

KEYWORD

nonn

AUTHOR

Labos Elemer, Dec 28 2000

EXTENSIONS

Offset corrected by Sean A. Irvine, Aug 11 2022

STATUS

approved

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Last modified September 30 22:28 EDT 2022. Contains 357107 sequences. (Running on oeis4.)