

A111391


Numbers n such that 11*10^n  1 is prime.


2



1, 9, 11, 17, 22, 29, 36, 37, 52, 166, 448, 2011, 3489, 4871, 6982, 10024, 16974, 33287, 47364, 58873, 126160
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OFFSET

1,2


COMMENTS

Numbers n such that 10^(n+1) + (10^n1) is a prime.


LINKS

Table of n, a(n) for n=1..21.
Gary Barnes, Primes of the form k*10^n1


MATHEMATICA

Do[ If[ PrimeQ[10^(n + 1) + (10^n  1)], Print[n]], {n, 9500}]


PROG

(PARI) is(n)=ispseudoprime(11*10^n1) \\ Charles R Greathouse IV, Jun 12 2017


CROSSREFS

Cf. A096209.
Sequence in context: A075824 A228951 A108113 * A077788 A137018 A182391
Adjacent sequences: A111388 A111389 A111390 * A111392 A111393 A111394


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Nov 15 2005


EXTENSIONS

a(16)a(19) from Ray Chandler, Sep 16 2013
a(20)a(21) from P. Kurtovic submitted by Ray Chandler, Sep 17 2013


STATUS

approved



