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A062623
Numbers k such that 57^k - 56^k is prime.
0
2, 19, 769, 773, 4507, 26183
OFFSET
1,1
COMMENTS
Terms greater than 1000 often correspond only to strong pseudoprimes. [Clarified by M. F. Hasler, Sep 15 2013]
a(7) > 10^5. - Robert Price, Dec 06 2012
PROG
(PARI) is(n)=ispseudoprime(57^n-56^n) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
nonn,hard
AUTHOR
Mike Oakes, May 18 2001, May 19 2001
EXTENSIONS
a(6) from Robert Price, Dec 06 2012
STATUS
approved