OFFSET
1,3
FORMULA
a(3n) is asymptotic to c*3^n, a(3n+1) to 2*c*3^n, a(3n+2) to 3*c*3^n where c=0.729407718249558020561155714549683618764251558505616....
PROG
(PARI) a(n)=if(n<3, 1, a(n-1)+if(n%3, a(n-2), a(n/3)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 11 2003
STATUS
approved