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 A004257 #47 Apr 26 2024 02:37:36
%S A004257 0,1,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,
%T A004257 5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
%U A004257 6,6,6,6,6,6,6,6,6,6,6,6,6
%N A004257 a(n) = round(log_2(n)).
%H A004257 T. D. Noe, <a href="/A004257/b004257.txt">Table of n, a(n) for n = 1..10000</a>
%F A004257 a(n) = floor(log_2(sqrt(2)*n)). - _Velin Yanev_, Dec 11 2016
%F A004257 Conjecture: a(n) = A000523(n^2) - A000523(n). - _Mikhail Kurkov_, Sep 11 2019
%t A004257 Round[Log[2,Range[90]]] (* _Harvey P. Dale_, Aug 26 2014 *)
%o A004257 (PARI) a(n) = round(log(n)/log(2)); \\ _Michel Marcus_, Dec 11 2016
%o A004257 (PARI) a(n) = {logint(n^2,2) - logint(n,2)} \\ _Andrew Howroyd_, Sep 11 2019
%o A004257 (Magma) [Round(Log(2,n)):n in [1..90]]; // _Marius A. Burtea_, Aug 02 2019
%Y A004257 Cf. A000523 (floored).
%K A004257 nonn
%O A004257 1,3
%A A004257 _N. J. A. Sloane_