A237614 - OEIS

%I #10 Feb 10 2014 21:19:26

%S 1,2,2,2,6,11,11,7,3,3,3,8,13,13,8,14,14,14,33,33,9,15,9,4,4,42,22,22,

%T 43,4,36,99,10,10,10,10,38,38,38,38,31,24,17,17,17,62,24,194,55,80,11,

%U 40,11,11,11,11,11,57,11,11,33,18,18,83,164,5,5,5,156,5

%N Least positive integer k with A000720(k*n) divisible by n, or 0 if such a number k does not exist.

%C According to the conjecture in A237597, we should always have 0 < a(n) < prime(n).

%H Zhi-Wei Sun, <a href="/A237614/b237614.txt">Table of n, a(n) for n = 1..10000</a>

%e a(3) = 2 since pi(2*3) = 3 is divisible by 3, but pi(1*3) = 2 is not.

%t Do[Do[If[Mod[PrimePi[k*n],n]==0,Print[n," ",k];Goto[aa]],{k,1,Prime[n]-1}];

%t Print[n," ",0];Label[aa];Continue,{n,1,70}]

%Y Cf. A000720, A237578, A237597, A237598, A237612.

%K nonn

%O 1,2

%A _Zhi-Wei Sun_, Feb 10 2014