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A091642
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Number of primes less than 10^n which do not contain the digit 8.
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10
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4, 23, 141, 915, 6375, 46799, 355805, 2774348, 22023132, 177273427, 1443074791, 11855541525, 98146301284, 817786989282
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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 8.
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EXAMPLE
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a(2) = 23 because of the 25 primes less than 10^2, 2 have at least one digit 8; 25-2 = 23.
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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], 8] == {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* Robert G. Wilson v, Feb 02 2004 *)
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PROG
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(Python)
from sympy import sieve # use slower primerange for larger terms
def a(n): return sum('8' not in str(p) for p in sieve.primerange(2, 10**n))
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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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