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 A213858 #21 Jul 30 2025 00:57:00 %S A213858 0,1,2,3,4,5,7,8,10,11,13,15,17,19,21,23,25,27,29,31,33,35,38,40,42, %T A213858 45,47,49,52,54,57,59,62,64,67,70,72,75,77,80,83,85,88,91,94,96,99, %U A213858 102,105,108,110,113,116,119,122,125,128,131,134,137,140,143,145,148 %N A213858 Least m such that n! <= 4^m. %H A213858 Harvey P. Dale, <a href="/A213858/b213858.txt">Table of n, a(n) for n = 1..1000</a> (Identical to file previously submitted by Clark Kimberling except for first term.) %e A213858 a(11) = 13 because 4^12 < 11! <= 4^13. %t A213858 Ceiling[Log[4,Range[100]!]] (* _Harvey P. Dale_, Jul 21 2016 *) %Y A213858 Cf. A213857. %K A213858 nonn,easy %O A213858 1,3 %A A213858 _Clark Kimberling_, Jul 17 2012 %E A213858 Corrected (a(1) changed to zero) by _Harvey P. Dale_, Jul 21 2016