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A054616
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a(n) = Sum_{d|n} phi(d)*9^(n/d).
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3
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0, 9, 90, 747, 6660, 59085, 532350, 4783023, 43053480, 387422001, 3486843810, 31381059699, 282430082700, 2541865828437, 22876797238470, 205891132215735, 1853020231912080, 16677181699666713, 150094635685484490, 1350851717672992251
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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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PROG
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(PARI) a(n) = if(n==0, 0, sumdiv(n, d, eulerphi(d)*9^(n/d))); \\ Altug Alkan, Mar 16 2018
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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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