A088640 Smallest number suffixed to concatenation of n times n gives a prime.

2, 1, 3, 1, 9, 7, 29, 1, 3, 7, 39, 1, 23, 1, 97, 1, 91, 37, 59, 9, 93, 19, 97, 61, 293, 61, 3, 1, 57, 7, 43, 61, 7, 53, 31, 127, 353, 67, 841, 187, 9, 3, 179, 429, 127, 97, 3, 319, 11, 51, 39, 191, 33, 3, 41, 7, 39, 47, 73, 81, 401, 57, 441, 571, 957, 997, 1, 19, 291, 173, 9, 417

Offset: 0

Author

Amarnath Murthy, Oct 27 2003

Keywords

• base
• nonn

Examples

			a(6) = 29 and 66666629 is prime.
		

Crossrefs

Cf. A088639.

Programs

Maple

a:= proc(n) local d, h, s;
      s:= parse(cat(0, n$n));
      for d from 0 do
        for h to 10^d-1 do
          if isprime(s+h) then return h fi
        od:
        s:= s*10;
      od
    end:
seq(a(n), n=0..75);  # Alois P. Heinz, Feb 11 2021

Extensions

More terms from Ray Chandler, Nov 01 2003

a(0)=2 prepended by Alois P. Heinz, Feb 11 2021