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A153431
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a(n) is the smallest number m such that all n+1 numbers m*10^k+1 k=0,1, ...,n are prime.
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2
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1, 1, 1, 4, 28, 28, 170926, 170926, 931371868, 15538734736, 89468493268, 6009549731752, 89984938946056, 43000687652274618
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OFFSET
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0,4
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COMMENTS
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If n<m and r=10^n*a(m)*a(n)-1 is prime then r has at least n+1
representations of the form p*q-(p+q)where p & q are prime.
For n>3, 7 divides a(n). a(10) is greater than 4*10^10.
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LINKS
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EXAMPLE
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28+1, 280+1, 2800+1, 28000+1, 280000+1 & 2800000+1 are prime and 28 is the smallest such number so a(5)=28.
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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