|
|
A020466
|
|
Primes that contain digits 4 and 9 only.
|
|
9
|
|
|
449, 499, 4999, 9949, 44449, 49499, 49999, 94949, 94999, 444449, 994949, 999499, 4444949, 4449449, 4944949, 4949449, 4999949, 4999999, 9444949, 9494999, 9944449, 9994499, 44444999, 44499449, 44944499, 44994949, 49444949, 49444999, 49494499
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
Flatten[Table[Select[FromDigits/@Tuples[{4, 9}, n], PrimeQ], {n, 8}]] (* Vincenzo Librandi, Jul 27 2012 *)
|
|
PROG
|
(PARI) is(N)=isprime(N)&&!#setminus(Set(digits(N)), [4, 9]) \\ M. F. Hasler, Sep 22 2020
|
|
CROSSREFS
|
Cf. A036319 (composite numbers having all their prime factors in this sequence).
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|