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A017919
Powers of sqrt(5) rounded down.
10
1, 2, 5, 11, 25, 55, 125, 279, 625, 1397, 3125, 6987, 15625, 34938, 78125, 174692, 390625, 873464, 1953125, 4367320, 9765625, 21836601, 48828125, 109183006, 244140625, 545915033, 1220703125, 2729575167
OFFSET
0,2
COMMENTS
a(n) is the total length (rounded down to integer) of the elements of a variant of a 5-element fractal after n iterations, starting with 5 elements, each of whose length is 1/5 (in some units). See illustration in the Links. - Kival Ngaokrajang, Feb 26 2015
LINKS
MATHEMATICA
Floor[(Sqrt[5])^Range[0, 40]] (* Vincenzo Librandi, Nov 20 2011 *)
PROG
(PARI) a(n)=sqrtint(5^n) \\ Charles R Greathouse IV, Nov 18 2011
(Magma) [Floor(Sqrt(5^n)): n in [0..40]]; // Vincenzo Librandi, Nov 20 2011
(Python)
from math import isqrt
def A017919(n): return isqrt(5**n) # Chai Wah Wu, Jun 19 2024
CROSSREFS
Sequence in context: A151529 A192922 A215091 * A017920 A228765 A006054
KEYWORD
nonn
STATUS
approved