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A128358 Numbers n such that n divides 18^n - 1. 10
1, 17, 289, 4913, 83521, 1419857, 5846759, 24054337, 24137569, 99394903, 408923729, 410338673, 1689713351, 6951703393, 6975757441, 28725126967, 118178957681, 118285781329, 118587876497, 486643291847, 488327158439 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

17 divides a(n) for n>1. a(n) = 17^(n-1) for n<7. a(7) = 20231*17^2.

LINKS

Table of n, a(n) for n=1..21.

PROG

(PARI) is(n)=Mod(18, n)^n==1 \\ Charles R Greathouse IV, Nov 04 2016

CROSSREFS

Cf. A001026 = Powers of 17. Cf. A015969 = numbers n such that n | 16^n + 1.

Sequence in context: A045607 A045606 A171291 * A015969 A001026 A178765

Adjacent sequences:  A128355 A128356 A128357 * A128359 A128360 A128361

KEYWORD

hard,nonn

AUTHOR

Alexander Adamchuk, Mar 01 2007

EXTENSIONS

a(8)-a(10) from Farideh Firoozbakht, Mar 05 2007

More terms from Ryan Propper, Dec 31 2007

a(20)-a(24) from Alexander Adamchuk, May 17 2010

STATUS

approved

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Last modified December 8 17:06 EST 2016. Contains 278946 sequences.