OFFSET
0,5
COMMENTS
Lim n->infinity {a(n+1)/a(n)} = 2. Contrast with Fibonacci sequence. Also a(n+1)/a(n) = 2 iff n+1 is square.
FORMULA
a(n) = sum a(n-k), k= 1 ... [sqrt(n)] for n>=2; a(0)=0; a(1)=1.
EXAMPLE
a(9) = a(6) + a(7) + a(8) = 5 + 8 + 13 = 26.
CROSSREFS
KEYWORD
nonn
AUTHOR
Rick L. Shepherd, Sep 04 2007
STATUS
approved