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Number of noncubes <= n.
3

%I #31 Dec 28 2024 00:21:34

%S 0,0,1,2,3,4,5,6,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,

%T 24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,

%U 47,48,49,50,51,52,53,54,55,56,57,58,59,60,60,61,62,63,64,65,66,67,68

%N Number of noncubes <= n.

%H Chai Wah Wu, <a href="/A064524/b064524.txt">Table of n, a(n) for n = 0..10000</a> (terms 0..1000 from Harry J. Smith)

%F a(n) = n - floor(CubicRoot(n)) = n-A048766(n).

%F G.f.: x/(1 - x)^2 - (1/(1 - x))*Sum_{k>=1} x^(k^3). - _Ilya Gutkovskiy_, Feb 16 2017

%o (PARI) a(n) = n - sqrtnint(n, 3); \\ _Michel Marcus_, Jun 18 2024

%o (Python)

%o from sympy import integer_nthroot

%o def A064524(n): return n-integer_nthroot(n,3)[0] # _Chai Wah Wu_, Jun 18 2024

%Y Cf. A007412, A048766.

%K nonn

%O 0,4

%A _Reinhard Zumkeller_, Oct 07 2001