|
| |
|
|
A091639
|
|
Number of primes less than 10^n which do not contain the digit 5.
|
|
10
|
|
|
|
3, 22, 136, 905, 6310, 46549, 354910, 2765749, 21955845, 176781643, 1439380189, 11827571824
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Table of n, a(n) for n=1..12.
|
|
|
FORMULA
|
Number of primes less than 10^n after removing any primes with at least one digit 5.
|
|
|
EXAMPLE
|
a(2) = 22 because of the 25 primes less than 10^2, 3 have at least one digit 5; 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], 5] == {}, c++ ]]; Print[c]; p--, {n, 1, 8}] (from Robert G. Wilson v Feb 02 2004)
|
|
|
CROSSREFS
|
a(n) + A091706(n) = A006880(n).
Cf. A091634, A091635, A091636, A091637, A091638, A091640, A091641, A091642, A091643.
Sequence in context: A006283 A100511 A033506 * A091636 A215051 A156089
Adjacent sequences: A091636 A091637 A091638 * A091640 A091641 A091642
|
|
|
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
|
|
|
STATUS
|
approved
|
| |
|
|
