OFFSET
1,3
LINKS
David A. Corneth, Table of n, a(n) for n = 1..538
EXAMPLE
44449 is the least prime of 5 digits containing just digits 4 and 9 so a(5) = 44449. - David A. Corneth, Oct 10 2019
MATHEMATICA
Join[{0, 0}, Table[SelectFirst[10*FromDigits[#]+9&/@Tuples[{4, 9}, n], PrimeQ], {n, 2, 20}]] (* Harvey P. Dale, Aug 20 2021 *)
PROG
(PARI) a(n) = my(s=4*(10^(n)-1)/9); forstep(i=1, 2^n-1, 2, fr = fromdigits(5 * binary(i)) + s; if(isprime(fr), return(fr))); 0 \\ David A. Corneth, Oct 10 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jan 04 1999
STATUS
approved