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A105042
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Numbers n such that 10n - 1 is prime.
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1
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2, 3, 6, 8, 9, 11, 14, 15, 18, 20, 23, 24, 27, 35, 36, 38, 39, 41, 42, 44, 45, 48, 50, 51, 57, 60, 62, 66, 71, 72, 74, 77, 81, 83, 84, 86, 92, 93, 101, 102, 104, 105, 107, 111, 113, 123, 125, 126, 128, 129, 132, 140, 141, 143, 144, 146, 149, 150, 155, 156, 158, 161, 162
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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If n = 2, then 10*n - 1 = 19 (prime).
If n = 18, then 10*n - 1 = 179 (prime).
If n = 36, then 10*n - 1 = 359 (prime).
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MAPLE
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a:= proc(n) if isprime(10*n-1) then n end if end proc: seq(a(n), n = 1 .. 200); # Emeric Deutsch, Aug 02 2009
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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