A114783 Smallest prime of the form: all ones followed by prime(n). a(n) >prime(n). 0 if no such prime exists.

0, 13, 0, 17, 1111111111111111111, 113, 1117, 11119, 1123, 1129, 131, 137, 11111141, 111143, 11111111111111111111111111111147, 1153, 11159, 11161, 167, 1171, 173, 179, 1111183, 1111189, 197, 11111101, 1103, 11111111111111107, 1109

Offset: 1

Author

Amarnath Murthy, Nov 17 2005

Keywords

• base
• nonn

Comments

Prime(n) is all zeros followed by prime(n). This is all ones followed by prime(n). Conjecture: No term is zero except a(1) = a(3) = 0.

Examples

			a(7) = 1117, as 117 is composite prime(8) = 17.
		

Crossrefs

Cf. A114784.

Programs

Mathematica

spf[n_]:=Module[{x=IntegerLength[n]+1,idn=IntegerDigits[n]}, While[ !PrimeQ[ FromDigits[ PadLeft[ idn,x,1]]],x++]; FromDigits[ PadLeft[ idn,x,1]]]; Join[{0,13,0},spf/@Prime[Range[4,30]]] (* Harvey P. Dale, May 22 2014 *)

Extensions

More terms from Joshua Zucker, May 06 2006