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Search: id:A088605
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| A088605 |
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a(n) is the beginning of the first set of n consecutive primes such that the concatenation of n with each of these primes is also prime. |
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+0
1
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OFFSET
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1,1
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COMMENT
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a(8) > 10^11, a(9) = 11408039 - Hans Havermann (pxp(AT)rogers.com), Sep 16 2005
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EXAMPLE
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a(3) = 7 because 7, 11, and 13 are 3 consecutive primes, and 37, 311, and 313 are all prime.
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MATHEMATICA
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<<NumberTheory`; Do[s = 0; l = {}; While[Length[l] < n, s++; l = List[Prime[s]]; k = 1; While[k < n, p = l[[k]]; AppendTo[l, NextPrime[p]]; k++ ]; l = ToString /@ l; l = Map[ToString[n] <> #&, l]; l = ToExpression /@ l; l = Select[l, PrimeQ]]; Print[Prime[s]], {n, 1, 30}]; (Propper)
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CROSSREFS
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Sequence in context: A132558 A072113 A105433 this_sequence A063562 A130475 A122902
Adjacent sequences: A088602 A088603 A088604 this_sequence A088606 A088607 A088608
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KEYWORD
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base,hard,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 15 2003
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EXTENSIONS
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Corrected, extended and edited by Ryan Propper (rpropper(AT)stanford.edu) and David Wasserman (wasserma(AT)spawar.navy.mil), Aug 14 2005
a(7) from Hans Havermann (pxp(AT)rogers.com), Sep 16 2005
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