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%I #19 Mar 27 2017 10:58:12
%S 0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,0,3,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,
%T 0,3,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,0,4,0,1,0,1,0,2,0,1,0,1,0,2,0,1,
%U 0,1,0,3,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0,1,0,3,0,1,0,1,0,2,0,1,0,1,0,2,0,1,0
%N Exponent of 3 in 2^n - 1.
%C Records: a(A025192(n)) = n and a(k) < n for k < A025192(n). [_Joerg Arndt_, Apr 07 2014]
%H T. D. Noe, <a href="/A168570/b168570.txt">Table of n, a(n) for n = 1..10000</a>
%e For n=6, 2^6 - 1 = 63. Greatest divisor of 63 which is a power of 3 is 9 (3^2).
%p a:= n-> padic[ordp](2^n-1, 3):
%p seq(a(n), n=1..120); # _Alois P. Heinz_, Mar 27 2017
%t Table[IntegerExponent[2^n - 1, 3], {n, 100}] (* _T. D. Noe_, Apr 13 2014 *)
%o (PARI) vector(100,n,valuation(2^n-1,3)) /* _Joerg Arndt_, Jun 13 2011 */
%Y Cf. A051064 (without the zeros).
%K nonn
%O 1,6
%A _Martins Opmanis_, Nov 30 2009
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