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A065334
2-exponents to represent 3-smooth numbers (A065332).
3
0, 1, 0, 2, 0, 1, 0, 3, 0, 0, 0, 2, 0, 0, 0, 4, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0
OFFSET
1,4
COMMENTS
For k > 0 with A065332(k) > 0: A065332(k) = (2^a(k)) * (3^A065335(k)).
FORMULA
a(n) = A007814(n) * A065333(n).
MATHEMATICA
a[n_] := If[n/2^(e = IntegerExponent[n, 2])/3^IntegerExponent[n, 3] == 1, e, 0]; Array[a, 100] (* Amiram Eldar, Feb 21 2021 *)
PROG
(PARI) A065334(n) = if(1==n, 0, my(f = factor(n)); if(f[#f~, 1] > 3, 0, valuation(n, 2))); \\ Antti Karttunen, Oct 09 2018
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Reinhard Zumkeller, Oct 29 2001
EXTENSIONS
Typo in formula corrected, erroneous comment removed by Antti Karttunen, Oct 09 2018
STATUS
approved