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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; internal format)
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OFFSET
| 0,1
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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 (davidwwilson(AT)comcast.net) 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
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CROSSREFS
| Cf. A109004.
Sequence in context: A172376 A010211 A066786 * A010210 A010212 A040151
Adjacent sequences: A109012 A109013 A109014 * A109016 A109017 A109018
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KEYWORD
| nonn,easy,mult
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AUTHOR
| Mitch Harris (Harris.Mitchell(AT)mgh.harvard.edu)
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