OFFSET
1,2
LINKS
EXAMPLE
a(53) = 7 because 53=(110101)_2 which contains (0)_2 = 0, (1)_2 = 1, (10)_2 = 2, (11)_2 = 3, (101)_2 = 5, (1101)_2 = 13 and (10101)_2 = 21. The one digit only contributes once as do two and zero.
CROSSREFS
KEYWORD
nonn
AUTHOR
Marko Riedel, May 08 2016
STATUS
approved