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A306855
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Primes of the form 10^i + 10^j - 1.
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1
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19, 109, 199, 1009, 1999, 10009, 10099, 100999, 199999, 1000099, 1000999, 19999999, 1000000009, 1000009999, 1000099999, 1009999999, 10000000999, 10000099999, 10999999999, 100999999999, 1000000009999, 1000000999999, 1099999999999, 10000000000099, 10009999999999, 100000000000099, 100000009999999
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OFFSET
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1,1
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COMMENTS
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Primes p such that p+1 is in A052216.
Primes of the following form in base 10: 1, followed by 0 or more 0's, then 1 or more 9's.
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LINKS
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MAPLE
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select(isprime, [seq(seq(10^n+10^m-1, m=1..n), n=1..15)]);
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MATHEMATICA
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Select[Flatten[Table[FromDigits[Join[PadRight[{1}, n, 0], PadRight[{}, m, 9]]], {n, 20}, {m, 20}]], PrimeQ]//Sort (* Harvey P. Dale, May 15 2021 *)
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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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STATUS
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approved
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