OFFSET
1,24
COMMENTS
LINKS
Eric Weisstein's World of Mathematics, Digital Root
FORMULA
a(n) = A035386(floor(n/3))*0^(n mod 3).
G.f.: Product_{j>=0} 1/(1 - x^(6+9*j)). - Robert Israel, Apr 13 2015
EXAMPLE
a(30) = #{24+6, 15+15, 6+6+6+6+6} = 3.
MAPLE
N:= 1000: # to get a(1) to a(N)
g:= mul(1/(1-x^(6+9*j)), j=0..floor((N-6)/9)):
S:= series(g, x, N+1):
seq(coeff(S, x, j), j=1..N); # Robert Israel, Apr 13 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Feb 12 2006
STATUS
approved