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A080086 Number of factors of 3 in the factorial of the n-th prime, counted with multiplicity. 4
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
FORMULA
a(n) = sum_{k=1..L} floor(prime(n) / 3^k), where L = log(p_n)/log(3).
MATHEMATICA
lst={}; Do[p=Prime[n]; s=0; While[p>1, p=IntegerPart[p/3]; s+=p; ]; AppendTo[lst, s], {n, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jul 28 2009 *)
Join[{0}, FactorInteger[#][[2, 2]]&/@(Prime[Range[2, 70]]!)] (* Harvey P. Dale, Sep 05 2014 *)
CROSSREFS
Sequence in context: A233564 A333222 A030326 * A229133 A015844 A114318
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 26 2003
STATUS
approved

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Last modified April 20 16:37 EDT 2024. Contains 371845 sequences. (Running on oeis4.)