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A218126
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Number of 9-ary sequences with primitive period n.
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2
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1, 9, 72, 720, 6480, 59040, 530640, 4782960, 43040160, 387419760, 3486725280, 31381059600, 282428998560, 2541865828320, 22876787671920, 205891132034880, 1853020145805120, 16677181699666560, 150094634909047920, 1350851717672992080, 12157665455570137920
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = Sum_{d|n} 9^d * mu(n/d) for n>0, a(0) = 1.
G.f.: 1 + 9 * Sum_{k>=1} mu(k) * x^k / (1 - 9*x^k). - Ilya Gutkovskiy, Apr 15 2021
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MAPLE
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with(numtheory):
a:= n-> `if`(n=0, 1, add(9^d*mobius(n/d), d=divisors(n))):
seq(a(n), n=0..30);
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PROG
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(PARI) a(n) = if (n==0, 1, sumdiv(n, d, 9^d*moebius(n/d))); \\ Michel Marcus, Apr 15 2021
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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