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A069246
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Primes which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).
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28
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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
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OFFSET
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1,1
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LINKS
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Giovanni Resta, Table of n, a(n) for n = 1..270 (terms 1..77 from Vincenzo Librandi, terms 78..145 from Zak Seidov)
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EXAMPLE
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86743 is prime and so are 867431, 867413, 867143, 861743, 816743, 186743. - Paolo P. Lava, Aug 10 2012
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MATHEMATICA
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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 *)
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PROG
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(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
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CROSSREFS
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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
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KEYWORD
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nonn,easy,base
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AUTHOR
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N. J. A. Sloane, Apr 14 2002
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EXTENSIONS
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More terms from Vladeta Jovovic, Apr 16 2002
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STATUS
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approved
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