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A109015 a(n) = gcd(n,12). 4
12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1, 12, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Periodic, with period = 12. - Harvey P. Dale, Dec 20 2018

LINKS

Table of n, a(n) for n=0..98.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,1).

FORMULA

a(n) = 1 + [2|n] + 2*[3|n] + 2*[4|n] + 2*[6|n] + 4*[12|n], where [x|y] = 1 when x divides y, 0 otherwise.

a(n) = a(n-12).

Multiplicative with a(p^e, 12) = gcd(p^e, 12). - David W. Wilson, Jun 12 2005

Dirichlet g.f.: zeta(s)*(1 + 1/2^s + 2/4^s)*(1 + 2/3^s). - R. J. Mathar, Apr 08 2011

MATHEMATICA

GCD[Range[0, 100], 12] (* or *) PadRight[{}, 120, {12, 1, 2, 3, 4, 1, 6, 1, 4, 3, 2, 1}] (* Harvey P. Dale, Dec 20 2018 *)

CROSSREFS

Cf. A109004.

Sequence in context: A010211 A335503 A066786 * A010210 A229193 A010212

Adjacent sequences:  A109012 A109013 A109014 * A109016 A109017 A109018

KEYWORD

nonn,easy,mult

AUTHOR

Mitch Harris

STATUS

approved

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Last modified August 1 01:59 EDT 2021. Contains 346377 sequences. (Running on oeis4.)