OFFSET
1,1
COMMENTS
Primes whose digit set is a subset of {1,3,9}.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..20000
Marianne Freiberger, Primes without 7s.
James Maynard, Primes with restricted digits, arXiv:1604.01041 [math.NT], 2016.
James Maynard and Brady Haran, Primes without a 7, Numberphile video (2019)
MATHEMATICA
Select[Prime[Range[1500]], IntegerQ[Log[3, Times@@IntegerDigits[#]]]&] (* or *) Table[Select[FromDigits/@Tuples[{1, 3, 9}, n], PrimeQ], {n, 5}]// Flatten (* Harvey P. Dale, Dec 31 2019 *)
PROG
(Magma) [p: p in PrimesUpTo(12000) | Set(Intseq(p)) subset [1, 3, 9]]; // Vincenzo Librandi, Jan 02 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Alois P. Heinz, Nov 20 2019
STATUS
approved