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A091643
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Number of primes less than 10^n which do not contain the digit 9.
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30
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4, 19, 108, 687, 4766, 35139, 267486, 2083814, 16531372, 133059504, 1082995490, 8896945667, 73651718719, 613664827254
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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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Number of primes less than 10^n after removing any primes with at least one digit 9.
a(n) <= max(4,24*(9^(n-2))) <= 1 + (9^n)/3 (see formula in A091634). - Chai Wah Wu, Sep 17 2018
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EXAMPLE
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a(2) = 19 because of the 25 primes less than 10^2, 6 have at least one digit 9; 25-6 = 19.
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MATHEMATICA
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NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; c = 0; p = 1; Do[ While[ p = NextPrim[p]; p < 10^n, If[ Position[ IntegerDigits[p], 9] == {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* Robert G. Wilson v, Feb 02 2004 *)
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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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