A230630 a(1)=0; thereafter a(n) = (1 + a(floor(n/2))) mod 3.

0, 1, 1, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1,4

Comments

For 2^i <= n < 2^(i+1), a(n) = (i mod 3).

Links

Antti Karttunen, Table of n, a(n) for n = 1..32768

Index entries for sequences related to binary expansion of n

Formula

a(n) = A000523(n) (mod 3). - John M. Campbell, Jul 15 2016

Maple

f:=proc(n) option remember; if n=1 then 0 else (1+f(floor(n/2))) mod 3; fi; end; [seq(f(n), n=1..120)];

Mathematica

Fold[Append[#1, Mod[1 + #1[[Floor[#2/2]]], 3]] &, {0}, Range[2, 105]] (* Michael De Vlieger, Oct 10 2017 *)

Prog

(PARI) a(n)=logint(n, 2)%3 \\ Charles R Greathouse IV, Jul 15 2016
(Scheme, with memoization-macro definec)
(definec (A230630 n) (if (= 1 n) 0 (modulo (+ 1 (A230630 (/ (- n (if (even? n) 0 1)) 2))) 3))) ;; Antti Karttunen, Oct 10 2017

Crossrefs

See A230629 for another version.

Cf. A000523, A030300, A030301.

Sequence in context: A306707 A180958 A295854 * A343957 A338505 A037867

Adjacent sequences: A230627 A230628 A230629 * A230631 A230632 A230633

Keyword

nonn,easy

Author

N. J. A. Sloane, Oct 30 2013

Status

approved