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A211682
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Prime numbers such that all the substrings of length <= 2 are primes.
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54
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2, 3, 5, 7, 23, 37, 53, 73, 373, 237373, 537373, 5373737, 53737373, 53737373737, 237373737373, 737373737373737, 53737373737373737, 373737373737373737373, 53737373737373737373737, 53737373737373737373737373, 373737373737373737373737373, 5373737373737373737373737373737
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OFFSET
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1,1
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COMMENTS
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A211681 restricted to primes. Contains A085823. In contrast to A085823 this sequence seems to be not finite (conjecture).
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LINKS
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EXAMPLE
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a(10)=237373, since all substrings of length <= 2 are primes (2, 3, 7, 23, 37, 73) and 237373 is prime.
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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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The originally submitted terms with index 20 and 21 are composite and have been erased therefore. - Hieronymus Fischer, Sep 24 2018
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STATUS
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approved
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