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A054613
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a(n) = Sum_{d|n} phi(d)*6^(n/d).
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3
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0, 6, 42, 228, 1344, 7800, 46956, 279972, 1681008, 10078164, 60474120, 362797116, 2176832112, 13060694088, 78364444284, 470185001040, 2821111589856, 16926659444832, 101559966840108, 609359740010604, 3656158500550080
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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)*6^(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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