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A080086
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Number of factors of 3 in the factorial of the n-th prime, counted with multiplicity.
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4
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0, 1, 1, 2, 4, 5, 6, 8, 9, 13, 14, 17, 18, 19, 21, 23, 27, 28, 31, 32, 34, 36, 40, 42, 46, 48, 49, 50, 53, 54, 61, 62, 66, 67, 71, 72, 75, 80, 81, 84, 86, 88, 93, 94, 95, 97, 102, 108, 110, 111, 112, 115, 116, 123, 126, 129, 131, 134, 136, 138, 139, 143, 151, 152, 153
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OFFSET
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1,4
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LINKS
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FORMULA
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a(n) = sum_{k=1..L} floor(prime(n) / 3^k), where L = log(p_n)/log(3).
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MATHEMATICA
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Join[{0}, FactorInteger[#][[2, 2]]&/@(Prime[Range[2, 70]]!)] (* Harvey P. Dale, Sep 05 2014 *)
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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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