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A091708
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Number of primes less than 10^n having at least one digit 7.
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10
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1, 9, 68, 549, 4819, 43506, 397756, 3681943, 34344296, 322199867, 3036544958, 28722439343, 272501681533, 2591959274190
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OFFSET
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1,2
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LINKS
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EXAMPLE
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a(1) = 1 because of the 4 primes less than 10^1, 1 has at least one digit 7.
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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], 7] != {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* Robert G. Wilson v, Feb 02 2004 *)
Table[Count[Prime[Range[PrimePi[10^n]]], _?(DigitCount[#, 10, 7]>0&)], {n, 12}] (* Harvey P. Dale, Mar 03 2013 *)
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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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EXTENSIONS
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STATUS
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approved
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