A060585 Write n in base 3, then (working from left to right) if the k-th digit of n is not equal to the digit to its left then the k-th digit of a(n) is 1, otherwise it is 0, and finally read the result as a base-2 number.

0, 1, 1, 3, 2, 3, 3, 3, 2, 6, 7, 7, 5, 4, 5, 7, 7, 6, 6, 7, 7, 7, 6, 7, 5, 5, 4, 12, 13, 13, 15, 14, 15, 15, 15, 14, 10, 11, 11, 9, 8, 9, 11, 11, 10, 14, 15, 15, 15, 14, 15, 13, 13, 12, 12, 13, 13, 15, 14, 15, 15, 15, 14, 14, 15, 15, 13, 12, 13, 15, 15, 14, 10, 11, 11, 11, 10, 11, 9, 9

Offset: 0

Author

Henry Bottomley, Apr 04 2001

Keywords

• base
• nonn

Comments

A ternary-to-binary map.

Each k appears A001316(k) times in the sequence.

Examples

			a(76) = 10 since 76 = 2211_3 and looking for changing digits produces 1010 which, read as if in binary, is 10.
		

Crossrefs

Cf. A001316, A060584, A060586, A060587.

Programs

PARI

a(n) = my(v=digits(n,3)); if(#v, forstep(k=#v,2,-1, v[k]=(v[k]!=v[k-1])); v[1]=1); fromdigits(v,2); \\ Kevin Ryde, Apr 15 2021

Formula

a(n) = 2*a(floor(n/3)) + A060584(n) = A060586(A060587(n)).

Extensions

Definition rewritten by Editors of OEIS, Apr 15 2021.