A271107 Numbers k such that 33*10^k + 1 is prime.

1, 2, 5, 6, 7, 8, 29, 47, 145, 205, 227, 505, 553, 600, 787, 809, 1305, 1447, 1593, 2285, 4763, 5679, 9133, 12516, 14869, 16536, 33402, 36085, 51933, 56443, 69133

Offset: 1

Author

Robert Price, Mar 30 2016

Keywords

• nonn
• base
• more

Comments

Numbers k such that the digits 33 followed by k-1 occurrences of the digit 0 followed by the digit 1 is prime (see Example section).

a(32) > 10^5.

Examples

			5 is in this sequence because 33*10^5+1 = 3300001 is prime.
Initial terms and associated primes:
a(1) = 1, 331;
a(2) = 2, 3301;
a(3) = 5, 3300001;
a(4) = 6, 33000001;
a(5) = 7, 330000001;
a(6) = 8, 3300000001, etc.
		

Links

• Makoto Kamada, Search for 330w1.

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A270974.

Programs

Mathematica

Select[Range[0, 100000], PrimeQ[33*10^#+1] &]

PARI

lista(nn) = for(n=1, nn, if(ispseudoprime(33*10^n+1), print1(n, ", "))); \\ Altug Alkan, Mar 31 2016