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A181354 Number of n-digit perfect cubes. 18

%I #32 Feb 12 2024 01:45:41

%S 2,2,5,12,25,53,116,249,535,1155,2487,5358,11545,24871,53584,115444,

%T 248715,535841,1154435,2487154,5358411,11544347,24871542,53584111,

%U 115443470,248715414,535841116,1154434691,2487154143,5358411166

%N Number of n-digit perfect cubes.

%C a(n) is also the total number of n-digit numbers requiring 1 positive cube in their representation as sum of cubes.

%C a(n) + A181376(n) + A181378(n) + A181380(n) + A181384(n) + A181401(n) + A181403(n) + A181405(n) + A171386(n) = A052268(n).

%C Differs from A062941 only at n=1, because 0 is considered a 0-digit, not a 1-digit number here. - _R. J. Mathar_, Jul 09 2011

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/WaringsProblem.html">Waring's Problem</a>.

%F a(n) = A061439(n) - A061439(n-1).

%p a:=n->ceil(10^(n/3))-ceil(10^((n-1)/3));

%t With[{c = Range[4650000]^3}, Length[#]&/@Table[Select[c, IntegerLength[#] == n &], {n, 20}]] (* _Harvey P. Dale_, Feb 01 2011 *)

%t Differences[Ceiling[10^(Range[0, 30]/3)]]

%Y Cf. A000578

%K nonn,base

%O 1,1

%A _Martin Renner_, Jan 28 2011

%E More terms from _T. D. Noe_, Feb 01 2011

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Last modified April 16 01:01 EDT 2024. Contains 371696 sequences. (Running on oeis4.)