A276492 Numbers k such that 5*10^k + 59 is prime.

1, 3, 7, 9, 10, 19, 21, 22, 43, 46, 58, 87, 216, 549, 604, 1147, 1858, 2952, 3684, 4057, 4246, 4354, 8212, 8289, 9013, 16968, 19107, 57754, 61348, 88254

Offset: 1

Author

Robert Price, Sep 05 2016

Keywords

• nonn
• more

Comments

For k > 1, numbers k such that the digit 5 followed by k-2 occurrences of the digit 0 followed by the digits 59 is prime (see Example section).

a(31) > 2*10^5.

Examples

			3 is in this sequence because 5*10^3 + 59 = 5059 is prime.
Initial terms and associated primes:
a(1) = 1, 109;
a(2) = 3, 5059;
a(3) = 7, 50000059;
a(4) = 9, 5000000059;
a(5) = 10, 50000000059, etc.
		

Links

• Makoto Kamada, Factorization of near-repdigit-related numbers.
• Makoto Kamada, Search for 50w59.

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Programs

Mathematica

Select[Range[0, 100000], PrimeQ[5*10^# + 59] &]

PARI

is(n)=ispseudoprime(5*10^n + 59) \\ Charles R Greathouse IV, Jun 13 2017