A017920 Powers of sqrt(5) rounded to nearest integer.
1, 2, 5, 11, 25, 56, 125, 280, 625, 1398, 3125, 6988, 15625, 34939, 78125, 174693, 390625, 873464, 1953125, 4367320, 9765625, 21836601, 48828125, 109183007, 244140625, 545915034, 1220703125, 2729575168
Offset: 0
Keywords
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..2000
Programs
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Magma
[Round(Sqrt(5)^n): n in [0..40]]; // Vincenzo Librandi, Nov 19 2011
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Mathematica
Floor[(Sqrt[5]^Range[0,40]+1/2)] (* Vincenzo Librandi, Nov 19 2011 *)
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PARI
a(n)=round(sqrt(5)^n) \\ Charles R Greathouse IV, Nov 18 2011
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Python
from math import isqrt def A017920(n): return (m:=isqrt(k:=5**n))+(k-m*(m+1)>=1) # Chai Wah Wu, Jun 19 2024