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Search: id:A083750
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| A083750 |
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Numbers n such that 2111131111...p(n-1)1111p(n) is prime. |
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1
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OFFSET
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1,1
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COMMENT
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Let fp(n,k) be the decimal concatenation of prime(n), k, and fp(n-1,k) for n > 1, and fp(1,k) = 2. Then a(n) = fp(n, 1111).
No more terms up to 6300.
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LINKS
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Farideh Firoozbakht, On Solution of puzzle 208 .
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EXAMPLE
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a(1)=85 because fp(85,1111)= 211113111151111...4331111439 is prime and fp(k,1111) is composite for k< 85 (prime(85)=439).
a(3)=304 because fp(304,1111)=211113111151111...199911112003 is a prime related to prime year 2003; this prime number has 2231 digits. fp(915,1111)=211113111151111...712911117151 is a prime with 7119 digits (prime(915)=7151).
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CROSSREFS
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Cf. A083677, A082549.
Sequence in context: A161479 A027453 A029471 this_sequence A043684 A043574 A043739
Adjacent sequences: A083747 A083748 A083749 this_sequence A083751 A083752 A083753
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KEYWORD
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nonn,base
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jun 17 2003
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EXTENSIONS
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Comment by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Oct 12 2009
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