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 A018020 #11 Sep 08 2022 08:44:44
%S A018020 1,3,7,15,37,92,225,555,1369,3375,8324,20528,50625,124852,307912,
%T A018020 759375,1872780,4618673,11390625,28091697,69280083,170859375,
%U A018020 421375454,1039201232,2562890625,6320631805,15588018474,38443359375,94809477069,233820277108
%N A018020 Powers of cube root of 15 rounded up.
%H A018020 Vincenzo Librandi, <a href="/A018020/b018020.txt">Table of n, a(n) for n = 0..200</a>
%t A018020 Table[Ceiling[15^(n/3)], {n, 0, 40}] (* _Vincenzo Librandi_, Jan 09 2014 *)
%o A018020 (Magma) [Ceiling(15^(n/3)): n in [0..40]]; // _Vincenzo Librandi_, Jan 09 2014
%Y A018020 Cf. 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), A018005 (k=10), A018008 (k=11), A018011 (k=12), A018014 (k=13), A018017 (k=14), this sequence (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 A018020 nonn
%O A018020 0,2
%A A018020 _N. J. A. Sloane_
%E A018020 More terms from _Vincenzo Librandi_, Jan 09 2014