This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A018005 #31 Sep 08 2022 08:44:44
%S A018005 1,3,5,10,22,47,100,216,465,1000,2155,4642,10000,21545,46416,100000,
%T A018005 215444,464159,1000000,2154435,4641589,10000000,21544347,46415889,
%U A018005 100000000,215443470,464158884,1000000000,2154434691,4641588834
%N A018005 Smallest number whose cube has n digits.
%C A018005 With offset 0, ((cube root of 10) to the power n) rounded up.
%C A018005 From _Carmine Suriano_, Mar 14 2020: (Start)
%C A018005 The terms corresponding to n = (20,21); (38,39); (41,42); (56,57); (59,60); (77,78); (80,81) ... are such that the square of first term starts with the digits of second term, and the square of second term starts with the digits of the first. For example, a(38)^2 = 2154434690032^2 = 4641588833613.... and a(39)^2 = 4641588833613^2 = 2154434690032...
%C A018005 (End)
%H A018005 Vincenzo Librandi, <a href="/A018005/b018005.txt">Table of n, a(n) for n = 1..200</a>
%e A018005 a(5) = 22, 22^3 = 10648 has 5 digits, while 21^3 = 9261 has 4 digits.
%t A018005 Table[Ceiling[10^(n/3)], {n, 0, 40}] (* _Vincenzo Librandi_, Jan 09 2014 *)
%o A018005 (Magma) [Ceiling(10^(n/3)): n in [0..40]]; // _Vincenzo Librandi_, Jan 09 2014
%Y A018005 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).
%K A018005 nonn,base,easy
%O A018005 1,2
%A A018005 _N. J. A. Sloane_
%E A018005 More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001