OFFSET
1,3
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
log a(n) ~ sqrt(n log phi) where phi is the golden ratio A001622. There are (log x/log phi)^2 + O(log x) members of this sequence up to x. - Charles R Greathouse IV, Jul 24 2012
EXAMPLE
14=13+1, so is in, however 17 is not expressible as Fib(i)+Fib(j).
PROG
(PARI) list(lim)=my(upper=log(lim*sqrt(5))\log((1+sqrt(5))/2)+1, t, tt, v=List([0, 1, 2])); if(fibonacci(t)>lim, t--); for(i=3, upper, t=fibonacci(i); for(j=2, i-1, tt=t+fibonacci(j); if(tt>lim, break, listput(v, tt)))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 24 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jon Perry, Jun 20 2003
STATUS
approved