A069589 Smallest prime in which the n-th significant digit is a 3.

3, 31, 307, 3001, 30011, 300007, 3000017, 30000001, 300000007, 3000000019, 30000000001, 300000000077, 3000000000013, 30000000000011, 300000000000089, 3000000000000037, 30000000000000029, 300000000000000011, 3000000000000000037, 30000000000000000041

Offset: 1

Author

Amarnath Murthy, Mar 25 2002

Keywords

• base
• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..996

Crossrefs

Cf. A069588.

Programs

Maple

seq(nextprime(3*10^(j-1)-1), j=1..32);

Mathematica

Join[{3},Table[NextPrime[FromDigits[PadRight[{3},n,0]]],{n,2,20}]] (* Harvey P. Dale, Jun 15 2015 *)

PARI

a(n) = nextprime(3*10^(n-1)); \\ Michel Marcus, Mar 31 2021

Python

from sympy import nextprime
def a(n): return nextprime(3*10**(n-1)-1)
print([a(n) for n in range(1, 21)]) # Michael S. Branicky, Mar 31 2021

Extensions

More terms from Sascha Kurz, Mar 28 2002