%I #10 Sep 08 2022 08:44:44

%S 1,3,8,21,58,160,441,1217,3357,9261,25551,70492,194481,536559,1480324,

%T 4084101,11267725,31086799,85766121,236622225,652822777,1801088541,

%U 4969066720,13709278307,37822859361,104350401111,287894844441,794280046581,2191358423330

%N Powers of cube root of 21 rounded up.

%H Vincenzo Librandi, <a href="/A018038/b018038.txt">Table of n, a(n) for n = 0..200</a>

%t Table[Ceiling[21^(n/3)], {n, 0, 40}] (* _Vincenzo Librandi_, Jan 10 2014 *)

%o (Magma) [Ceiling(21^(n/3)): n in [0..40]]; // _Vincenzo Librandi_, Jan 10 2014

%Y 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), A018020 (k=15), A018023 (k=16), A018026 (k=17), A018029 (k=18), A018032 (k=19), A018035 (k=20), this sequence (k=21), A018041 (k=22), A018044 (k=23), A018047 (k=24).

%K nonn

%O 0,2

%A _N. J. A. Sloane_

%E More terms from _Vincenzo Librandi_, Jan 10 2014