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A059671
Numbers n such that n*10^n - 1 is prime.
13
2, 3, 8, 11, 15, 39, 60, 72, 77, 117, 183, 252, 396, 1745, 2843, 4665, 5364, 524427
OFFSET
1,1
COMMENTS
No further terms up to 500000 (see Harvey link). - Ray Chandler, Apr 10 2016
REFERENCES
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 117, p. 41, Ellipses, Paris 2008.
MATHEMATICA
Do[ If[ PrimeQ[ n*10^n - 1 ], Print[ n ] ], {n, 1, 2500} ]
PROG
(PARI) is(n)=ispseudoprime(n*10^n-1) \\ Charles R Greathouse IV, Mar 01 2017
CROSSREFS
Sequence in context: A364217 A050557 A039000 * A212771 A119116 A138756
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Feb 05 2001
EXTENSIONS
a(15) - a(17) from Farideh Firoozbakht, Apr 01 2009
a(18) communicated by Jeppe Stig Nielsen, Apr 03 2023
STATUS
approved