|
|
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
|
|
|
FORMULA
|
Number of primes less than 10^n after removing any primes with at least one digit 4.
|
|
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
|
|
|
KEYWORD
|
more,nonn,base
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|