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

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..2000

Mathematica

Floor[(Sqrt[5]^Range[0, 40]+1/2)] (* Vincenzo Librandi, Nov 19 2011 *)

Prog

(PARI) a(n)=round(sqrt(5)^n) \\ Charles R Greathouse IV, Nov 18 2011
(Magma) [Round(Sqrt(5)^n): n in [0..40]]; // Vincenzo Librandi, Nov 19 2011
(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

Crossrefs

Cf. A017919, A017921.

Sequence in context: A192922 A215091 A017919 * A228765 A006054 A106805

Adjacent sequences: A017917 A017918 A017919 * A017921 A017922 A017923

Keyword

nonn

Author

N. J. A. Sloane

Status

approved