A103069 Numbers n such that 8*10^n + 3 is prime.

0, 1, 31, 105, 113, 369, 1359, 6219, 105571, 150975

Offset

1,3

Comments

a(11) > 2*10^5. - Robert Price, Aug 19 2015

Links

Table of n, a(n) for n=1..10.

Makoto Kamada, Prime numbers of the form 800...003.

Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.

Index entries for primes involving repunits.

Formula

a(n) = A101056(n-1) + 1, for n>1.

Example

For n = 2 we have 8*10^1+3 = 8*10+3 = 83, which is prime.

Mathematica

Do[ If[ PrimeQ[ 8*10^n + 3], Print[ n ]], {n, 0, 10000}]

Prog

(PARI) is(n)=ispseudoprime(8*10^n+3) \\ Charles R Greathouse IV, Jun 12 2017

Crossrefs

Cf. A101056.

Sequence in context: A075936 A221902 A289134 * A206526 A141877 A057230

Adjacent sequences: A103066 A103067 A103068 * A103070 A103071 A103072

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 19 2005

Extensions

Prepended a(1) = 0 by Robert Price, Aug 19 2015

a(9)-a(10) from Robert Price, Aug 19 2015

Status

approved