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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 (list; graph; refs; listen; history; text; internal format)
 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. 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

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Last modified August 7 22:54 EDT 2024. Contains 375018 sequences. (Running on oeis4.)