A168570 Exponent of 3 in 2^n - 1.

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, 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, 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

Offset: 1

Author

Martins Opmanis, Nov 30 2009

Keywords

• nonn

Comments

Records: a(A025192(n)) = n and a(k) < n for k < A025192(n). [Joerg Arndt, Apr 07 2014]

Examples

			For n=6, 2^6 - 1 = 63. Greatest divisor of 63 which is a power of 3 is 9 (3^2).
		

Links

• T. D. Noe, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A051064 (without the zeros).

Programs

Maple

a:= n-> padic[ordp](2^n-1, 3):
seq(a(n), n=1..120);  # Alois P. Heinz, Mar 27 2017

Mathematica

Table[IntegerExponent[2^n - 1, 3], {n, 100}] (* T. D. Noe, Apr 13 2014 *)

PARI

vector(100,n,valuation(2^n-1,3)) /* Joerg Arndt, Jun 13 2011 */