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A108052 Integers n such that 10^n+19 is a prime number. 27
1, 3, 5, 7, 10, 11, 17, 59, 81, 108, 574, 629, 1069, 1759, 2063, 2682, 9174, 40929, 42457, 66033 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Verified terms through 9174. - Robert Price, May 24 2010

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "10019".

No other terms <= 100,000. - Robert Price, Mar 03 2011

LINKS

Table of n, a(n) for n=1..20.

Makoto Kamada, List of near-repdigit-related prime numbers.

Index entries for primes involving repunits.

EXAMPLE

n = 7 we have 10^7+19 = 10000000+19 = 10000019, which is prime.

MATHEMATICA

Select[Range[2*10^3], PrimeQ[10^#+19]&] - Vladimir Joseph Stephan Orlovsky, Apr 29 2008

PROG

(PARI) is(n)=ispseudoprime(10^n+19) \\ Charles R Greathouse IV, Apr 28 2015

CROSSREFS

Cf. A049054, A088274, A088275, A095688.

Sequence in context: A189009 A206812 A189372 * A046868 A225240 A104309

Adjacent sequences:  A108049 A108050 A108051 * A108053 A108054 A108055

KEYWORD

more,nonn

AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Jun 01 2005

EXTENSIONS

a(17)=9174 from Ryan Propper, Jan 02 2008

Edited by Ray Chandler, Dec 23 2010

a(18)=40929 and a(19)=42457 from Robert Price, Dec 27 2010

a(20)=66033 from Robert Price, Jan 09 2011

STATUS

approved

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Last modified September 26 05:09 EDT 2017. Contains 292502 sequences.