OFFSET
1,1
FORMULA
a(n)=phi*n+O(1) where phi=(1+sqrt(5))/2
PROG
(PARI) an=vector(100); a(n)=if(n<0, 0, an[n]); an[1]=2; for(n=2, 100, an[n]=if(setsearch(Set(vector(n-1, i, a(i))), n), a(n-1)+3, a(n-2)+1))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Oct 24 2005
STATUS
approved