A068958 Smallest value of k such that p | (10^k + 1), where p is the n-th prime; or 0 if no such k exists.

3, 1, 3, 8, 9, 11, 14, 0, 0, 0, 0, 23, 0, 29, 30, 0, 0, 4, 0, 0, 22, 48, 2, 17, 0, 54, 56, 21, 65, 4, 23, 74, 0, 39, 0, 83, 0, 89, 90, 0, 96, 49, 0, 15, 111, 0, 114, 116, 0, 15, 25, 128, 131, 134, 0, 0, 14, 0, 73, 0, 0, 156, 0, 55, 168, 0, 58, 16, 0, 183, 93, 189, 191, 194, 0, 100

Offset: 4

Author

Amarnath Murthy, Apr 01 2002

Keywords

• nonn

Examples

			a(4) = 3 as the fourth prime 7 divides 1001.
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 4..10000

Programs

PARI

a(n)=my(p=prime(n),m=Mod(1,p)); for(k=1,znorder(10*m), if(-1==m*=10, return(k))); 0 \\ Charles R Greathouse IV, Jun 18 2013

Extensions

More terms from Sascha Kurz, Jan 03 2003