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A168570
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Exponent of 3 in 2^n - 1.
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2
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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
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OFFSET
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1,6
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COMMENTS
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Records: a(A025192(n)) = n and a(k) < n for k < A025192(n). [Joerg Arndt, Apr 07 2014]
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..10000
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EXAMPLE
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For n=6, 2^6 - 1 = 63. Greatest divisor of 63 which is a power of 3 is 9 (3^2).
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MAPLE
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a:= n-> padic[ordp](2^n-1, 3):
seq(a(n), n=1..120); # Alois P. Heinz, Mar 27 2017
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MATHEMATICA
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Table[IntegerExponent[2^n - 1, 3], {n, 100}] (* T. D. Noe, Apr 13 2014 *)
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PROG
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(PARI) vector(100, n, valuation(2^n-1, 3)) /* Joerg Arndt, Jun 13 2011 */
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CROSSREFS
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Cf. A051064 (without the zeros).
Sequence in context: A248908 A133565 A239704 * A340928 A355742 A267860
Adjacent sequences: A168567 A168568 A168569 * A168571 A168572 A168573
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KEYWORD
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nonn
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AUTHOR
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Martins Opmanis, Nov 30 2009
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STATUS
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approved
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