OFFSET
1,1
EXAMPLE
1, 10, 11, 11, 100, 101, 110, 111, 1000, 1000, 1000, 1001, 1001, ... <- A108787
..1..1..0..1..1..1..1..1..0..0..1..0... <- first difference are this sequence
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Philippe Deléham, Jul 09 2005
STATUS
approved