OFFSET
1,1
COMMENTS
All terms after 3 are composite.
FORMULA
a(n) = 3*A007931(n). - Michel Marcus, Mar 30 2017
MATHEMATICA
Table[Map[FromDigits, Tuples[{3, 6}, {k}]], {k, 5}] // Flatten (* Michael De Vlieger, Mar 30 2017 *)
PROG
(Magma) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {3, 6}]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Mar 30 2017
STATUS
approved