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A176597
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Double primes: concatenation of the n-th prime with itself.
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2
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22, 33, 55, 77, 1111, 1313, 1717, 1919, 2323, 2929, 3131, 3737, 4141, 4343, 4747, 5353, 5959, 6161, 6767, 7171, 7373, 7979, 8383, 8989, 9797, 101101, 103103, 107107, 109109, 113113, 127127, 131131, 137137, 139139, 149149, 151151, 157157, 163163
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OFFSET
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1,1
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LINKS
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EXAMPLE
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Concatenation 2 and 2 is 22; 3 and 3 is 33; 5 and 5 is 55; etc.
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MATHEMATICA
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dp[n_] := Module[{idn = IntegerDigits[n]}, FromDigits[Join[idn, idn]]]; dp /@ Prime[Range[40]] (* Harvey P. Dale, Jun 02 2011 *)
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PROG
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(Magma) [Seqint(Intseq(p) cat Intseq(p)): p in PrimesUpTo(200)]; // Vincenzo Librandi, Mar 14 2013
(PARI) a(n) = { my(p=Str(prime(n))); eval(concat(p, p)); } /* Joerg Arndt, Mar 14 2013 */
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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