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 A049416 #14 Feb 16 2022 23:56:01 %S A049416 3,9,31,99,316,999,3162,9999,31622,99999,316227,999999,3162277, %T A049416 9999999,31622776,99999999,316227766,999999999,3162277660,9999999999, %U A049416 31622776601,99999999999,316227766016,999999999999,3162277660168 %N A049416 Largest number whose square has n digits. %C A049416 a(n) + A180416(n) + A180425(n) + A167615(n) = A002283(n). %H A049416 Vincenzo Librandi, <a href="/A049416/b049416.txt">Table of n, a(n) for n = 1..1000</a> %F A049416 a(n) = ceiling(sqrt(10^n)) - 1. %e A049416 31^2 = 961, but 32^2 = 1024, hence a(3) = 31. %e A049416 a(4) = 99: 99^2 = 9801 has 4 digits, while 100^2 = 10000 has 5 digits. %t A049416 Ceiling[Sqrt[10^Range[40]]-1] (* _Harvey P. Dale_, Sep 30 2011 *) %o A049416 (Magma) [Ceiling(Sqrt(10^n))-1: n in [1..30]]; // _Vincenzo Librandi_, Oct 01 2011 %Y A049416 Cf. A061433, A049415. Equals A017936 - 1. %K A049416 nonn,base,easy,nice %O A049416 1,1 %A A049416 Ulrich Schimke (ulrschimke(AT)aol.com) %E A049416 More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001