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A159353 a(n) = the smallest positive integer such that a(n) *(2^n -2) is a multiple of n. 5
1, 1, 1, 2, 1, 3, 1, 4, 3, 5, 1, 6, 1, 7, 5, 8, 1, 9, 1, 10, 7, 11, 1, 12, 5, 13, 9, 2, 1, 15, 1, 16, 11, 17, 35, 18, 1, 19, 13, 20, 1, 21, 1, 22, 3, 23, 1, 24, 7, 25, 17, 26, 1, 27, 55, 28, 19, 29, 1, 30, 1, 31, 21, 32, 13, 33, 1, 34, 23, 5, 1, 36, 1, 37, 25, 38, 77, 39, 1, 40, 27, 41, 1, 42 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

This is not the same sequence as sequence A032742, where A032742(n) = the largest proper divisor of n. See A146077 for numbers n such that the sequences A032742 and A159353 differ.

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = Denominator((2^n - 2)/n). - Juri-Stepan Gerasimov, Sep 09 2014

MATHEMATICA

Array[Block[{k = 1}, While[! Divisible[k (2^# - 2), #], k++]; k] &, 84] (* Michael De Vlieger, Oct 30 2017 *)

PROG

(MAGMA) [Denominator((2^n-2)/n): n in [1..84]]; // Juri-Stepan Gerasimov, Sep 09 2014

(PARI) a(n)=my(k=1); while((2^n-2)*k%n != 0, k++); return(k) \\ Edward Jiang, Sep 09 2014

(PARI) a(n)=denominator(lift(Mod(2, n)^n-2)/n) \\ Charles R Greathouse IV, Sep 11 2014

CROSSREFS

Cf. A000918, A146077.

Sequence in context: A326139 A325641 A325563 * A032742 A060654 A291329

Adjacent sequences:  A159350 A159351 A159352 * A159354 A159355 A159356

KEYWORD

nonn

AUTHOR

Leroy Quet, Apr 11 2009

EXTENSIONS

Extended by Ray Chandler, Apr 11 2009

STATUS

approved

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Last modified November 30 05:31 EST 2020. Contains 338781 sequences. (Running on oeis4.)