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A069246
Primes which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).
28
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)
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.
Sequence in context: A155128 A176589 A077314 * A340870 A253850 A087578
KEYWORD
nonn,easy,base
AUTHOR
N. J. A. Sloane, Apr 14 2002
EXTENSIONS
More terms from Vladeta Jovovic, Apr 16 2002
STATUS
approved