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 A091643 Number of primes less than 10^n which do not contain the digit 9. 30

%I

%S 4,19,108,687,4766,35139,267486,2083814,16531372,133059504,1082995490,

%T 8896945667,73651718719,613664827254

%N Number of primes less than 10^n which do not contain the digit 9.

%F Number of primes less than 10^n after removing any primes with at least one digit 9.

%F a(n) = A006880(n) - A091710(n).

%F a(n) <= max(4,24*(9^(n-2))) <= 1 + (9^n)/3 (see formula in A091634). - _Chai Wah Wu_, Sep 17 2018

%e a(2) = 19 because of the 25 primes less than 10^2, 6 have at least one digit 9; 25-6 = 19.

%t 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 *)

%Y Cf. A091634, A091635, A091636, A091637, A091638, A091639, A091640, A091641, A091642.

%K more,nonn,base

%O 1,1

%A _Enoch Haga_, Jan 30 2004

%E Edited and extended by _Robert G. Wilson v_, Feb 02 2004

%E a(9)-a(12) from _Donovan Johnson_, Feb 14 2008

%E a(13) from _Robert Price_, Nov 08 2013

%E a(14) from _Giovanni Resta_, Mar 20 2017

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Last modified November 22 16:31 EST 2019. Contains 329396 sequences. (Running on oeis4.)