OFFSET
0,3
LINKS
Zoran Šunić, Tree morphisms, transducers and integer sequences, arXiv:math/0612080 [math.CO], 2006, see after proposition 5.4.
FORMULA
a(n) = Sum_{j=0..floor(log_2(n))} 3^j*((-1)^j*floor((n/2^j + 1)/2) mod 3). - Corrected by Stefano Spezia, Oct 27 2018
MATHEMATICA
a[n_]:=Sum[3^j*(Mod[(-1)^j*Floor[(n/2^j + 1)/2], 3]), {j, 0, Floor[Log2[n]]}]; Array[a, 80, 0] (* Stefano Spezia, Oct 27 2018 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Henry Bottomley, Jun 06 2000
STATUS
approved