OFFSET
1,2
COMMENTS
LINKS
Eric Weisstein's World of Mathematics, Digital Root
EXAMPLE
a(10) = #{10, 5+5, 2+2+2+2+2, 10x1} = 4;
a(11) = #{11, 10+1, 11x1} = 3;
a(12) = #{12, 10+1+1, 6+6, 4+4+4, 3+3+3+3, 2+2+2+2+2+2, 12x1} = 7.
PROG
(Haskell)
a114102 n = length $ filter (== 1) $
map (length . nub . (map a010888)) $ ps 1 n
where ps x 0 = [[]]
ps x y = [t:ts | t <- [x..y], ts <- ps t (y - t)]
-- Reinhard Zumkeller, Feb 04 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Feb 12 2006
STATUS
approved