A213855 - OEIS

%I #13 Jun 13 2021 03:21:12

%S 1,1,2,2,3,4,4,5,6,7,7,8,9,9,10,11,12,12,13,14,15,15,16,17,18,18,19,

%T 20,21,22,22,23,24,25,25,26,27,28,28,29,30,31,32,32,33,34,35,36,36,37,

%U 38,39,39,40,41,42,43,43,44,45,46,47,47,48

%N Least m > 0 such that m! * 4^m >= n!.

%H Clark Kimberling, <a href="/A213855/b213855.txt">Table of n, a(n) for n = 1..1000</a>

%e a(5) = 3 because (4^2)*2! < 5! <= (4^3)*3!.

%p A213855 := proc(n)

%p         for m from 1 do

%p                 if (4^m)*m! >= n! then

%p                         return m;

%p                 end if;

%p         end do:

%p end proc: # _R. J. Mathar_, Jul 18 2012

%t Table[m=1; While[n!>(4^m)*m!, m++]; m, {n,1,100}]

%Y Cf. A213854.

%K nonn,easy

%O 1,3

%A _Clark Kimberling_, Jul 17 2012