OFFSET
0,2
COMMENTS
Write n in base 3, then (working from left to right) if the k-th digit of n is equal to the digit to the left of it then this is the k-th digit of a(n), otherwise the k-th digit of a(n) is the element of {0,1,2} which has not just been compared, then read result as a base 3 number.
LINKS
FORMULA
a(n) = 3a([n/3])+(-[n/3]-n mod 3) = 3a([n/3]) + A060588(n).
EXAMPLE
a(76) = 46 since 76 written in base 3 is 2211; this gives a first digit of 1( = 3-2-0), a second digit of 2( = 2 = 2), a third digit of 0( = 3-1-2) and a fourth digit of 1( = 1 = 1); 1201 base 3 is 46.
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Henry Bottomley, Apr 04 2001
STATUS
approved