OFFSET
1,1
COMMENTS
Inspired by Sun's conjecture in A224197: Also, bases b such that the number (with digits) [1;4;9] in base b is prime.
All terms are congruent to 4 (mod 6), i.e., a(n) = 4 + 6 x(n) with x=(0, 1, 5, 7, 11, 12, 15, 18, 20, 26, 27, 32, 33, 40, 42, 48, 55, 56, 61, 68, 71, 75, 76,...)
MATHEMATICA
Select[Range[1000], PrimeQ[#^2+4#+9]&] (* Harvey P. Dale, Sep 23 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Apr 01 2013
STATUS
approved