This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A017920 #24 Jun 19 2024 10:35:44 %S A017920 1,2,5,11,25,56,125,280,625,1398,3125,6988,15625,34939,78125,174693, %T A017920 390625,873464,1953125,4367320,9765625,21836601,48828125,109183007, %U A017920 244140625,545915034,1220703125,2729575168 %N A017920 Powers of sqrt(5) rounded to nearest integer. %H A017920 Vincenzo Librandi, <a href="/A017920/b017920.txt">Table of n, a(n) for n = 0..2000</a> %t A017920 Floor[(Sqrt[5]^Range[0,40]+1/2)] (* _Vincenzo Librandi_, Nov 19 2011 *) %o A017920 (PARI) a(n)=round(sqrt(5)^n) \\ _Charles R Greathouse IV_, Nov 18 2011 %o A017920 (Magma) [Round(Sqrt(5)^n): n in [0..40]]; // _Vincenzo Librandi_, Nov 19 2011 %o A017920 (Python) %o A017920 from math import isqrt %o A017920 def A017920(n): return (m:=isqrt(k:=5**n))+(k-m*(m+1)>=1) # _Chai Wah Wu_, Jun 19 2024 %Y A017920 Cf. A017919, A017921. %K A017920 nonn %O A017920 0,2 %A A017920 _N. J. A. Sloane_