OFFSET
1,12
COMMENTS
LINKS
Eric Weisstein's World of Mathematics, Digital Root
FORMULA
a(n) = A035382(floor(n/3))*0^(n mod 3).
EXAMPLE
a(21) = #{21, 12+3+3+3, 3+3+3+3+3+3+3} = 3.
CROSSREFS
KEYWORD
nonn,base,changed
AUTHOR
Reinhard Zumkeller, Feb 12 2006
STATUS
approved