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A078626
Primes p which concatenated with p+2 give a prime.
1
7, 37, 61, 109, 151, 181, 211, 271, 277, 331, 337, 367, 421, 439, 457, 487, 541, 619, 661, 691, 727, 751, 829, 859, 877, 907, 1039, 1087, 1129, 1201, 1237, 1279, 1321, 1399, 1489, 1549, 1609, 1621, 1699, 1741, 1777, 1831, 1999, 2341, 2347, 2767, 2851
OFFSET
1,1
LINKS
EXAMPLE
37 is a prime which, concatenated with 37+2=39, gives 3739, a prime; so 37 belongs to the sequence.
MATHEMATICA
a = {}; For[i = 1, i <= 10^3, i++, p = Prime[i]; If[PrimeQ[ToExpression[ToString[p] <> ToString[p + 2]]], a = Append[a, p]]]; a
conQ[n_]:=PrimeQ[FromDigits[Join[IntegerDigits[n], IntegerDigits[n+2]]]]; Select[Prime[Range[500]], conQ] (* Harvey P. Dale, May 28 2014 *)
CROSSREFS
Sequence in context: A217561 A003521 A155943 * A093389 A093342 A336494
KEYWORD
base,easy,nonn
AUTHOR
Joseph L. Pe, Dec 11 2002
STATUS
approved