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A128887
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Numbers n such that the number formed by the concatenation of the consecutive integers from 5 to n is prime.
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0
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OFFSET
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1,1
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COMMENTS
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Primes of this form are rare. 2 and 5 are the only beginning numbers less than 100 that form more than 2 primes for all ending numbers less than 1000.
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LINKS
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EXAMPLE
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The 2nd entry forms the number 567891011121314151617 which is prime.
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PROG
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(PARI) consecprimes(n, m) = { local(a, x, y); a=""; for(x=m, n, a=concat(a, Str(x)); y=eval(a); if(ispseudoprime(y), print(x", "y) ) ) }
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CROSSREFS
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KEYWORD
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more,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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