A069246 Primes which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).

3, 7, 13, 31, 103, 109, 151, 181, 193, 367, 571, 601, 613, 811, 1117, 1831, 4519, 6871, 11119, 11317, 11467, 13171, 16141, 17167, 18211, 18457, 27241, 38917, 55381, 71317, 81199, 81931, 86743, 114031, 139861, 141667, 151687, 179203, 200191

Offset

1,1

Links

Giovanni Resta, Table of n, a(n) for n = 1..270 (terms 1..77 from Vincenzo Librandi, terms 78..145 from Zak Seidov)

Example

86743 is prime and so are 867431, 867413, 867143, 861743, 816743, 186743. - Paolo P. Lava, Aug 10 2012

Mathematica

d[n_]:=IntegerDigits[n]; ins[n_]:=FromDigits/@Table[Insert[d[n], 1, k], {k, Length[d[n]]+1}]; Select[Prime[Range[20000]], And@@PrimeQ/@ins[#] &] (* Jayanta Basu, May 20 2013 *)

Prog

(Magma) [p: p in PrimesUpTo(210000) | forall{m: t in [0..#Intseq(p)] | IsPrime(m) where m is (Floor(p/10^t)*10+1)*10^t+p mod 10^t}]; // Bruno Berselli, Sep 03 2012

Crossrefs

Prime subsequence of A068679.

Cf. A215417, A215419 - A215421.

Sequence in context: A155128 A176589 A077314 * A340870 A253850 A087578

Adjacent sequences: A069243 A069244 A069245 * A069247 A069248 A069249

Keyword

nonn,easy,base

Author

N. J. A. Sloane, Apr 14 2002

Extensions

More terms from Vladeta Jovovic, Apr 16 2002

Status

approved