login
A017979
Powers of cube root of 2 rounded down.
24
1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 25, 32, 40, 50, 64, 80, 101, 128, 161, 203, 256, 322, 406, 512, 645, 812, 1024, 1290, 1625, 2048, 2580, 3250, 4096, 5160, 6501, 8192, 10321, 13003, 16384, 20642, 26007, 32768, 41285, 52015, 65536, 82570, 104031
OFFSET
0,4
COMMENTS
Rounding has no effect when n is a multiple of 3, because then obviously (2^(1/3))^n = 2^(n/3). - Alonso del Arte, Jan 04 2014
LINKS
EXAMPLE
a(2) = 1 because the cube root of 2 squared is 1.5874...
a(3) = 2 because the cube root of 2 cubed is 2 exactly.
a(4) = 2 because the cube root of 2 to the fourth power is 2.519842...
MATHEMATICA
Table[Floor[(2^(1/3))^n], {n, 0, 49}] (* Alonso del Arte, Jan 04 2014 *)
PROG
(Magma) [Floor(2^(n/3)): n in [0..50]]; // Vincenzo Librandi, Jan 06 2014
(Python)
from sympy import integer_nthroot
def A017979(n): return integer_nthroot(1<<n, 3)[0] # Chai Wah Wu, Jun 18 2024
CROSSREFS
Sequences of the type: Powers of cube root of (k) rounded down: this sequence (k=2), A017982 (k=3), A017985 (k=4), A017988 (k=5), A017991 (k=6), A017994 (k=7), A018000 (k=9), A018003 (k=10), A018006 (k=11), A018009 (k=12), A018012 (k=13), A018015 (k=14), A018018 (k=15), A018021 (k=16), A018024 (k=17), A018027 (k=18), A018030 (k=19), A018033 (k=20), A018036 (k=21), A018039 (k=22), A018042 (k=23), A018045 (k=24).
Sequence in context: A179241 A316082 A157046 * A140881 A316081 A238708
KEYWORD
nonn
EXTENSIONS
a(44)-a(50) from Alex Ratushnyak, Jan 04 2014
STATUS
approved