login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A091640 Number of primes less than 10^n which do not contain the digit 6. 10
4, 23, 136, 897, 6367, 46706, 355148, 2770239, 21984207, 176966593, 1440765209, 11838096715, 98014747908, 816769206831 (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 6.

a(n) = A006880(n) - A091707(n).

EXAMPLE

a(2) = 23 because of the 25 primes less than 10^2, 2 have at least one digit 6; 25-2 = 23.

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

CROSSREFS

Cf. A091634, A091635, A091636, A091637, A091638, A091639, A091641, A091642, A091643.

Sequence in context: A193808 A038723 A302761 * A237362 A067110 A290052

Adjacent sequences:  A091637 A091638 A091639 * A091641 A091642 A091643

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 16 21:10 EDT 2019. Contains 328103 sequences. (Running on oeis4.)