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A062586
Numbers k such that 20^k - 19^k is prime.
1
5, 17, 109, 1979, 6899, 7331, 18661, 79621, 81649
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OFFSET
1,1
COMMENTS
Terms k > 1000 may correspond to (unproven) strong pseudoprimes.
LINKS
Table of n, a(n) for n=1..9.
Henri Lifchitz and Renaud Lifchitz,
Top probable primes of the form 20^p-19^p
PROG
(PARI) is(n)=ispseudoprime(20^n-19^n) \\
Charles R Greathouse IV
, Jun 12 2017
CROSSREFS
Cf.
A000043
,
A057468
,
A059801
,
A059802
,
A062572
-
A062666
.
Sequence in context:
A267143
A331636
A234797
*
A301641
A067710
A197912
Adjacent sequences:
A062583
A062584
A062585
*
A062587
A062588
A062589
KEYWORD
nonn
,
hard
AUTHOR
Mike Oakes
, May 18 2001, May 19 2001
EXTENSIONS
a(7)-a(9) found by
Jean-Louis Charton
in February and March 2011
Edited by
M. F. Hasler
, Sep 16 2013
STATUS
approved
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Last modified April 24 06:39 EDT 2024. Contains 371920 sequences. (Running on oeis4.)