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A010057 a(n) = 1 if n is a cube, else 0. 25

%I

%S 1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,

%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,

%U 0,0,0,0,0,0,0,0,0,0,0,0,0

%N a(n) = 1 if n is a cube, else 0.

%C Multiplicative with a(p^e) = 1 if 3 divides e, 0 otherwise. - _Mitch Harris_, Jun 09 2005

%C a(A000578(n)) = 1; a(A007412(n)) = 0. - _Reinhard Zumkeller_, Oct 22 2011

%C a(n) = A000007(sum(A010872(A124010(n,k))): k = 1..A001221(n)) for n > 0. - _Reinhard Zumkeller_, Jun 21 2013

%C If n has 4 divisors, a(n) = bigomega(n) - 2. - _Wesley Ivan Hurt_, Jun 06 2014

%D E. Landau, Elementary Number Theory, translation by Jacob E. Goodman of Elementare Zahlentheorie (Vol. I_1 (1927) of Vorlesungen ueber Zahlentheorie), by Edmund Landau, with added exercises by Paul T. Bateman and E. E. Kohlbecker, Chelsea Publishing Co., New York, 1958, pp. 31-32.

%H Reinhard Zumkeller, <a href="/A010057/b010057.txt">Table of n, a(n) for n = 0..10000</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%F Dirichlet generating function: zeta(3s). - _Franklin T. Adams-Watters_, Sep 11 2005

%F a(n) = f(n,0) with f(x,y) = if x>0 then f(x-3*y*(y+1),y+1) else 0^(-x). - _Reinhard Zumkeller_, Sep 27 2008

%F a(n) = 1 + floor(n^(1/3)) - ceiling(n^(1/3)). - _Wesley Ivan Hurt_, Jun 06 2014

%F a(n) = floor(n^(1/3)) - floor((n-1)^(1/3)). - _Mikael Aaltonen_, Feb 24 2015

%t Table[ Boole[ IntegerQ[n^(1/3)]], {n, 0, 80}] (* _Jean-Fran├žois Alcover_, Jun 10 2013 *)

%o (Haskell)

%o a010057 0 = 1

%o a010057 n = fromEnum $ all ((== 0) . (`mod` 3)) $ a124010_row n

%o a010057_list = concatMap (\x -> 1 : replicate (a003215 x - 1) 0) [0..]

%o -- _Reinhard Zumkeller_, Jun 21 2013, Oct 22 2011

%o (PARI) a(n) = ispower(n, 3); \\ _Michel Marcus_, Feb 24 2015

%Y Cf. A000578.

%Y Cf. A003215. - _Reinhard Zumkeller_, Sep 27 2008

%K nonn,easy,mult

%O 0,1

%A _N. J. A. Sloane_, March 15 1996

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Last modified August 29 01:49 EDT 2015. Contains 261184 sequences.