A270339 Numbers k such that (11*10^k + 19)/3 is prime.

1, 2, 3, 9, 17, 18, 20, 24, 29, 36, 48, 114, 126, 135, 153, 170, 241, 363, 483, 579, 681, 948, 2483, 2798, 3081, 5137, 5640, 6890, 7080, 12600, 16929, 24253, 24793, 35546, 52956, 69645, 133831, 206688

Offset: 1

Author

Robert Price, Mar 15 2016

Keywords

• nonn
• more

Comments

For k > 1, numbers k such that the digit 3 followed by k-2 occurrences of the digit 6 followed by the digits 73 is prime (see Example section).

a(39) > 3*10^5.

Examples

			3 is in this sequence because (11*10^3 + 19)/3 = 3673 is prime.
Initial terms and associated primes:
a(1) = 1, 43;
a(2) = 2, 373;
a(3) = 3, 3673;
a(4) = 9, 3666666673;
a(5) = 17, 366666666666666673, etc.
		

Links

• Makoto Kamada, Search for 36w73.

Crossrefs

Cf. A056654, A268448, A269303.

Programs

Mathematica

Select[Range[0, 100000], PrimeQ[(11*10^# + 19)/3] &]

PARI

is(n)=isprime((11*10^n + 19)/3) \\ Charles R Greathouse IV, Mar 16 2016

Extensions

a(37) from Robert Price, Sep 16 2018

a(38) from Robert Price, Jul 25 2024