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A091638 Number of primes less than 10^n which do not contain the digit 4. 10
4, 22, 136, 903, 6361, 46545, 354123, 2761106, 21925170, 176544507, 1437663500, 11814853749, 97837428598, 815398741896 (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 4.

a(n) = A006880(n) - A091705(n).

EXAMPLE

a(2) = 22 because of the 25 primes less than 10^2, 3 have at least one digit 4; 25-3 = 22.

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], 4] == {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (* Robert G. Wilson v, Feb 02 2004 *)

CROSSREFS

Cf. A091634, A091635, A091636, A091637, A091639, A091640, A091641, A091642, A091643.

Sequence in context: A143648 A069835 A007196 * A142984 A283055 A097593

Adjacent sequences:  A091635 A091636 A091637 * A091639 A091640 A091641

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 June 17 04:26 EDT 2019. Contains 324183 sequences. (Running on oeis4.)