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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 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 Adjacent sequences:  A078623 A078624 A078625 * A078627 A078628 A078629 KEYWORD base,easy,nonn AUTHOR Joseph L. Pe, Dec 11 2002 STATUS approved

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Last modified September 20 04:40 EDT 2020. Contains 337264 sequences. (Running on oeis4.)