A124911 - OEIS

%I #7 Mar 14 2024 17:01:01

%S 0,1,2,4,1,2,3,16,4,20,8,2,18,9,3,22,16,10,4,26,20,14,8,5,2,24,18,15,

%T 9,6,3,28,22,19,16,13,10,7,4,29,26,23,20,17,14,11,8,5,33,30,27,24,52,

%U 21,18,15,43,12,9,37,6,3,31,28,56,25,22,50,19,47,16,13,41,10,38,7,35,4,60

%N a(n) = least integer j>=0 such that n = floor((5^j)/(2^k)) for some integer k>=0.

%C The k-sequence is A124919.

%H Robert Israel, <a href="/A124911/b124911.txt">Table of n, a(n) for n = 1..10000</a>

%e 1=[5^0/2^0], 2=[5^1/2^1], 3=[5^2/2^3], 4=[5^4/2^7], ...,

%e   so j-sequence=(0,1,2,4,...); k-sequence=(0,1,3,7,...).

%p N:= 100: # for a(1) .. a(N)

%p V:=Vector(N,-1): count:= 0:

%p for j from 0 while count < N do

%p   x:= 5^j;

%p   k0:= max(0, floor(log[2](x/N)));

%p   x:= x/2^(k0-1);

%p   for k from k0 do

%p     x:= x/2;

%p     if x < 1 then break fi;

%p     m:= floor(x);

%p     if m <= N and V[m] = -1 then V[m]:= j; count:= count+1 fi

%p od od:

%p convert(V, list); # _Robert Israel_, Mar 14 2024

%Y Cf. A124919.

%K nonn

%O 1,3

%A _Clark Kimberling_, Nov 13 2006