OFFSET
0,3
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
FORMULA
a(n) = n - a(floor(n/3))*3, a(0) = 0.
a(n) = 9*a(floor(n/9)) + (n mod 9) mod 3. - Reinhard Zumkeller, Sep 26 2015
EXAMPLE
n = 123 = '11120' --> '10100' = 90 = a(123).
PROG
(Haskell)
a105186 0 = 0
a105186 n = 9 * a105186 n' + mod t 3
where (n', t) = divMod n 9
-- Reinhard Zumkeller, Sep 26 2015
(PARI) a(n) = fromdigits(digits(n, 9)%3, 9); \\ Kevin Ryde, May 20 2020
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Apr 11 2005
STATUS
approved