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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 (list; graph; refs; listen; history; text; internal format)
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.

LINKS

Table of n, a(n) for n=1..17.

Steven Harvey, Generalized Woodall Search

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: A173269 A050557 A039000 * A212771 A119116 A138756

Adjacent sequences:  A059668 A059669 A059670 * A059672 A059673 A059674

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Feb 05 2001

EXTENSIONS

a(15) - a(17) from Farideh Firoozbakht, Apr 01 2009

STATUS

approved

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Last modified July 2 09:13 EDT 2020. Contains 335398 sequences. (Running on oeis4.)