|
| |
|
|
A065333
|
|
Characteristic function of 3-smooth numbers, i.e. numbers of the form 2^i*3^j (i, j >= 0).
|
|
11
| |
|
|
1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| a(n) = signum(A065332(n)), where signum = A057427. a(n) = if A065330(n) = 1 then 1 else 0 = 1 - signum(A065330(n) - 1).
|
|
|
LINKS
| Index entries for characteristic functions
|
|
|
FORMULA
| a(n) = if n = A003586(k) for some k then 1 else 0.
a(n) = Prod(0^floor(p/4): p prime and p|n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 19 2004
Multiplicative with a(2^e) = a(3^e) = 1, a(p^e) = 0 for prime p > 3. Dirichlet g.f. 1/(1-2^-s)/(1-3^-s). - Frank Adams-Watters (FrankTAW(AT)Netscape.net), Sep 01 2006
a(n) = 0^(A038502(A000265(n)) - 1). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Sep 28 2008]
a(n)=sum(d divides n, mu(6*d)) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 18 2009]
|
|
|
PROG
| (PARI) a(n)=sumdiv(n, d, moebius(6*d)) [From Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 18 2009]
(PARI) a(n)=3^valuation(n, 3)<<valuation(n, 2)==n \\ Charles R Greathouse IV, Aug 21 2011
|
|
|
CROSSREFS
| Sequence in context: A117198 A054525 A174852 * A127972 A103451 A103452
Adjacent sequences: A065330 A065331 A065332 * A065334 A065335 A065336
|
|
|
KEYWORD
| mult,nonn,easy
|
|
|
AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 29 2001
|
| |
|
|
