A117626 Least prime which stays prime when end digits (on both sides) are repeated n times.

2, 131, 113, 137, 197, 113, 139, 139, 223, 199, 137, 229, 127, 137, 271, 461, 167, 113, 131, 137, 421, 149, 167, 389, 337, 191, 419, 239, 263, 113, 373, 593, 211, 223, 683, 251, 137, 277, 359, 127, 281, 347, 193, 277, 151, 197, 199, 1321, 337, 1399, 547, 157

Offset

0,1

Links

Table of n, a(n) for n=0..51.

Example

We thus have successively the derived primes: 11311, 1111333, 111137777, 11111977777, 1111111333333, 111111139999999, ... .

Mathematica

f[n_] := Block[{k = 1}, While[id = IntegerDigits@ Prime@ k; !PrimeQ[ FromDigits@ Join[ Table[id[[1]], {n}], id, Table[id[[ -1]], {n}]]], k++ ]; Prime@k]; Table[ f@n, {n, 0, 51}] (* Robert G. Wilson v *)

Crossrefs

Sequence in context: A354054 A303445 A158110 * A084549 A142251 A125633

Adjacent sequences: A117623 A117624 A117625 * A117627 A117628 A117629

Keyword

base,nonn

Author

Lekraj Beedassy, Apr 08 2006

Extensions

More terms from Robert G. Wilson v, Apr 12 2006

Status

approved