|
|
A105186
|
|
Replace odd-positioned digits with 0 in ternary representation of n.
|
|
1
|
|
|
0, 1, 2, 0, 1, 2, 0, 1, 2, 9, 10, 11, 9, 10, 11, 9, 10, 11, 18, 19, 20, 18, 19, 20, 18, 19, 20, 0, 1, 2, 0, 1, 2, 0, 1, 2, 9, 10, 11, 9, 10, 11, 9, 10, 11, 18, 19, 20, 18, 19, 20, 18, 19, 20, 0, 1, 2, 0, 1, 2, 0, 1, 2, 9, 10, 11, 9, 10, 11, 9, 10, 11, 18, 19, 20, 18, 19, 20, 18, 19, 20, 81, 82
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
FORMULA
|
a(n) = n - a(floor(n/3))*3, a(0) = 0.
|
|
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
(PARI) a(n) = fromdigits(digits(n, 9)%3, 9); \\ Kevin Ryde, May 20 2020
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|