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

1,2

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.

Links

Table of n, a(n) for n=1..29.

Example

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

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 *)

Crossrefs

Cf. A114784.

Sequence in context: A073867 A114782 A065112 * A094902 A252056 A096069

Adjacent sequences: A114780 A114781 A114782 * A114784 A114785 A114786

Keyword

base,nonn

Author

Amarnath Murthy, Nov 17 2005

Extensions

More terms from Joshua Zucker, May 06 2006

Status

approved