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%I #26 Sep 08 2022 08:44:43
%S 1,2,2,2,3,4,4,6,7,8,11,13,16,21,26,32,41,51,64,81,102,128,162,204,
%T 256,323,407,512,646,813,1024,1291,1626,2048,2581,3251,4096,5161,6502,
%U 8192,10322,13004,16384,20643,26008,32768,41286,52016,65536,82571,104032
%N Powers of cube root of 2 rounded up.
%H Vincenzo Librandi, <a href="/A017981/b017981.txt">Table of n, a(n) for n = 0..1000</a>
%t Table[Ceiling[(2^(1/3))^n], {n, 0, 300}] (* _Vincenzo Librandi_, Jan 05 2014 *)
%o (PARI) a(n) = ceil(sqrtn(2, 3)^n); \\ _Michel Marcus_, Jan 03 2014
%o (Python)
%o def icbrt(a):
%o sr = 1 << (int.bit_length(int(a)) >> 1)
%o while a < sr*sr*sr: sr>>=1
%o b = sr>>1
%o while b:
%o s = sr+b
%o if a >= s*s*s: sr = s
%o b>>=1
%o return sr
%o for n in range(100): print(1+icbrt(2**n-1), end=",")
%o # _Alex Ratushnyak_, Jan 04 2014
%o (Magma) [Ceiling(2^(n/3)): n in [1..60]]; // _Vincenzo Librandi_, Jan 05 2014
%Y Cf. A017979.
%K nonn
%O 0,2
%A _N. J. A. Sloane_.
%E a(44)-a(50) from _Alex Ratushnyak_, Jan 02 2014
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