A020466 Primes that contain digits 4 and 9 only.

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

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: A344827 A345314 A107666 * A142420 A319060 A339532

Adjacent sequences: A020463 A020464 A020465 * A020467 A020468 A020469

Keyword

nonn,base

Author

David W. Wilson

Status

approved