OFFSET
1,2
COMMENTS
Numbers of A031945 do not appear in this sequence.
EXAMPLE
The fifth term cannot be 5(base10)=11(base4), 6(base10)=12(base4), 7(base10)=13(base4), 8(base10)=20(base4) or 9(base10)=21(base4) because each of them has either a 0 or a 1 in its base-4 representation, which it would have in common with 4(base10)=10(base4). So a(5)=10(base10)=22(base4) which displays only digits of 2 in base 4.
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
R. J. Mathar, Mar 31 2009
STATUS
approved