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A102737
Numbers k such that 3*10^k - 11 is prime.
0
1, 4, 7, 11, 14, 16, 22, 29, 36, 40, 65, 139, 149, 204, 842, 1031, 1331, 1345, 1505, 1894, 3386, 3526, 11092, 23836, 37836, 138811, 182614
OFFSET
1,2
COMMENTS
Some of the larger entries may only correspond to probable primes.
Numbers corresponding to terms <= 842 are certified primes. - Klaus Brockhaus, Feb 16 2005
Next term > 12500. - Ryan Propper, Jul 21 2006
For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 9 followed by the digits 89 is prime. - Robert Price, Nov 25 2017
a(28) > 2*10^5. - Robert Price, Jul 04 2018
MATHEMATICA
Select[Range[1, 500], PrimeQ[3*10^# - 11]&] (* Julien Kluge, Sep 19 2016 *)
PROG
(PARI) is(n)=ispseudoprime(3*10^n - 11) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A219051 A376355 A310723 * A310724 A212447 A172513
KEYWORD
more,nonn
AUTHOR
Tom Mueller (muel4503(AT)uni-trier.de), Feb 08 2005
EXTENSIONS
a(15)-a(19) from Klaus Brockhaus, Feb 16 2005
a(20)-a(23) from Ryan Propper, Jul 21 2006
a(24)-a(25) from Robert Price, Nov 25 2017
a(26) from Robert Price, Jul 04 2018
a(27) from Robert Price, Jul 25 2018
STATUS
approved