

A103002


Numbers n such that 5*10^n  7 is prime.


2



1, 3, 4, 8, 14, 16, 24, 61, 80, 87, 104, 108, 144, 2157, 3325, 4122, 20718, 51163, 140744
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OFFSET

1,2


COMMENTS

Also numbers n such that 4*10^n + 9*R_n  6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
a(20) > 2*10^5.  Robert Price, Sep 15 2015


LINKS

Table of n, a(n) for n=1..19.
Makoto Kamada, Prime numbers of the form 499...993.
Index entries for primes involving repunits.


FORMULA

a(n) = A101739(n) + 1.


MATHEMATICA

Do[ If[ PrimeQ[5*10^n  7], Print[n]], {n, 0, 10000}]


PROG

(PARI) is(n)=ispseudoprime(5*10^n7) \\ Charles R Greathouse IV, Jun 06 2017


CROSSREFS

Cf. A002275, A108837, A101739.
Sequence in context: A049893 A307043 A218381 * A310012 A181408 A004979
Adjacent sequences: A102999 A103000 A103001 * A103003 A103004 A103005


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Jan 17 2005


EXTENSIONS

Addition of a(17)a(18) from Kamada data by Robert Price, Dec 10 2010
a(19) from Robert Price, Sep 15 2015


STATUS

approved



