A018005 Smallest number whose cube has n digits.
1, 3, 5, 10, 22, 47, 100, 216, 465, 1000, 2155, 4642, 10000, 21545, 46416, 100000, 215444, 464159, 1000000, 2154435, 4641589, 10000000, 21544347, 46415889, 100000000, 215443470, 464158884, 1000000000, 2154434691, 4641588834
Offset: 1
Examples
a(5) = 22, 22^3 = 10648 has 5 digits, while 21^3 = 9261 has 4 digits.
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..200
Crossrefs
Cf. A061434, A061439, and powers of cube root of k ceiling up: A017981 (k=2), A017984 (k=3), A017987 (k=4), A017990 (k=5), A017993 (k=6), A017996 (k=7), A018002 (k=9), this sequence (k=10), A018008 (k=11), A018011 (k=12), A018014 (k=13), A018017 (k=14), A018020 (k=15), A018023 (k=16), A018026 (k=17), A018029 (k=18), A018032 (k=19), A018035 (k=20), A018038 (k=21), A018041 (k=22), A018044 (k=23), A018047 (k=24).
Programs
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Magma
[Ceiling(10^(n/3)): n in [0..40]]; // Vincenzo Librandi, Jan 09 2014
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Mathematica
Table[Ceiling[10^(n/3)], {n, 0, 40}] (* Vincenzo Librandi, Jan 09 2014 *)
Extensions
More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001
Comments