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A091643 Number of primes less than 10^n which do not contain the digit 9. 30
4, 19, 108, 687, 4766, 35139, 267486, 2083814, 16531372, 133059504, 1082995490, 8896945667, 73651718719, 613664827254 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..14.

FORMULA

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

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

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

EXAMPLE

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

MATHEMATICA

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 *)

CROSSREFS

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

Sequence in context: A241839 A218183 A206227 * A323620 A306183 A241840

Adjacent sequences:  A091640 A091641 A091642 * A091644 A091645 A091646

KEYWORD

more,nonn,base

AUTHOR

Enoch Haga, Jan 30 2004

EXTENSIONS

Edited and extended by Robert G. Wilson v, Feb 02 2004

a(9)-a(12) from Donovan Johnson, Feb 14 2008

a(13) from Robert Price, Nov 08 2013

a(14) from Giovanni Resta, Mar 20 2017

STATUS

approved

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Last modified October 14 00:30 EDT 2019. Contains 327991 sequences. (Running on oeis4.)