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A072087 Least k such that A072084(k) = n. +0
2
1, 3, 7, 9, 31, 21, 127, 27, 49, 93, 3583, 63, 8191, 381, 217, 81, 131071, 147, 524287, 279, 889, 10749, 14680063, 189, 961, 24573, 343, 1143, 1073479679, 651, 2147483647, 243, 25081, 393213, 3937, 441, 266287972351, 1572861, 57337, 837 (list; graph; listen)
OFFSET

1,2

COMMENT

If p is a Mersenne-prime then a(p) = 2^p - 1 (A000120(2^n-1)=n), for other primes p: a(p) > 2^p - 1.

This sequence may be multiplicative. - Mitch Harris, Apr 19 2005

FORMULA

Completely multiplicative with a(p) = A061712(p). - David W. Wilson (davidwwilson(AT)comcast.net), Aug 03 2005

CROSSREFS

Cf. A000120, A000043.

Sequence in context: A018827 A057840 A123481 this_sequence A031161 A031882 A075982

Adjacent sequences: A072084 A072085 A072086 this_sequence A072088 A072089 A072090

KEYWORD

nonn,mult

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Jun 14 2002

EXTENSIONS

More terms from David W. Wilson (davidwwilson(AT)comcast.net), Aug 03 2005

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.


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