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A178466
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Primes prime(k) such that the concatenation prime(k+1)//prime(k) is also prime.
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0
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3, 47, 53, 61, 131, 173, 199, 211, 233, 257, 353, 523, 587, 607, 619, 647, 653, 751, 797, 971, 991, 997, 1103, 1123, 1231, 1381, 1553, 1777, 1913, 1973, 1987, 2297, 2333, 2341, 2399, 2677, 2861, 3049, 3191, 3259, 3607, 3637, 3761, 3989
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OFFSET
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1,1
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COMMENTS
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53, 211, 653, 997, ... are also in A088712.
The role of the two primes is swapped in comparison to A030459.
The result of the concatenation is in A088784.
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LINKS
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FORMULA
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EXAMPLE
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The prime 53 is in the sequence because the next prime is 59 and 5953 is a prime.
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MAPLE
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read("transforms") ;
for n from 1 to 600 do p := ithprime(n) ; q := nextprime(p) ; r := digcat2(q, p) ; if isprime(r) then printf("%d, ", p) ; end if; end do: # R. J. Mathar, Jan 27 2011
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MATHEMATICA
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Transpose[Select[Partition[Prime[Range[600]], 2, 1], PrimeQ[FromDigits[ Flatten[ IntegerDigits/@Reverse[#]]]]&]][[1]] (* Harvey P. Dale, Feb 02 2011 *)
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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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STATUS
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approved
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