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 A017981 Powers of cube root of 2 rounded up. 23
 1, 2, 2, 2, 3, 4, 4, 6, 7, 8, 11, 13, 16, 21, 26, 32, 41, 51, 64, 81, 102, 128, 162, 204, 256, 323, 407, 512, 646, 813, 1024, 1291, 1626, 2048, 2581, 3251, 4096, 5161, 6502, 8192, 10322, 13004, 16384, 20643, 26008, 32768, 41286, 52016, 65536, 82571, 104032 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 MATHEMATICA Table[Ceiling[(2^(1/3))^n], {n, 0, 300}] (* Vincenzo Librandi, Jan 05 2014 *) PROG (PARI) a(n) = ceil(sqrtn(2, 3)^n); \\ Michel Marcus, Jan 03 2014 (Python) def icbrt(a):     sr = 1L << (long.bit_length(long(a)) >> 1)     while a < sr*sr*sr:  sr>>=1     b = sr>>1     while b:       s = sr+b       if a >= s*s*s:  sr = s       b>>=1     return sr for n in range(100):  print str(1+icbrt(2**n-1))+', ', # Alex Ratushnyak, Jan 04 2014 (MAGMA) [Ceiling(2^(n/3)): n in [1..60]]; // Vincenzo Librandi, Jan 05 2014 CROSSREFS Cf. A017979. Sequence in context: A035381 A096938 A130084 * A274759 A274157 A005863 Adjacent sequences:  A017978 A017979 A017980 * A017982 A017983 A017984 KEYWORD nonn AUTHOR EXTENSIONS a(44)-a(50) from Alex Ratushnyak, Jan 02 2014 STATUS approved

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