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 A017958 #18 Jul 08 2025 06:20:25 %S A017958 1,4,18,76,324,1374,5832,24743,104976,445375,1889568,8016758,34012224, %T A017958 144301645,612220032,2597429617,11019960576,46753733110,198359290368, %U A017958 841567195983,3570467226624,15148209527700 %N A017958 Powers of sqrt(18) rounded down. %H A017958 Vincenzo Librandi, <a href="/A017958/b017958.txt">Table of n, a(n) for n = 0..800</a> %F A017958 a(n) = floor(sqrt(18^n)). - _Vincenzo Librandi_, Jun 24 2011 %e A017958 sqrt(18)^2 = 18, so a(2) = 18. %e A017958 sqrt(18)^3 = 76.3675323681471326352911911..., so a(3) = 76. %e A017958 sqrt(18)^4 = 18^2 = 324, so a(4) = 324. %e A017958 sqrt(18)^5 = 1374.61558262664838743524143993..., so a(5) = 1374. %t A017958 Floor[Sqrt[18]^Range[0, 35]] (* _Alonso del Arte_, Dec 07 2017 *) %o A017958 (Magma) [Floor(Sqrt(18^n)): n in [0..30]]; // _Vincenzo Librandi_, Jun 24 2011 %o A017958 (PARI) a(n)=sqrtint(18^n) \\ _Charles R Greathouse IV_, Nov 18 2011 %Y A017958 Cf. A001027 (bisection) %K A017958 nonn,easy %O A017958 0,2 %A A017958 _N. J. A. Sloane_