

A020466


Primes that contain digits 4 and 9 only.


8



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
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OFFSET

1,1


LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..20000 (first 1000 terms from Vincenzo Librandi)
James Maynard and Brady Haran, Primes without a 7, Numberphile video (2019)


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).
Sequence in context: A071104 A087700 A107666 * A142420 A319060 A105376
Adjacent sequences: A020463 A020464 A020465 * A020467 A020468 A020469


KEYWORD

nonn,base


AUTHOR

David W. Wilson


STATUS

approved



