21 May 12, 10:16PM
(21 May 12, 02:04PM)Roflcopter Wrote:(21 May 12, 10:00AM)Sepehr Wrote: ...
It's a nice solution but more work than direct calculation with Binet's formula and geometric summation and relies on tricks that won't work for generalised version of these problems. Binet's formula is easily proved with standard recurrence relation tools.
While Binet's formula is more elegant, it kind of feels wrong having an answer that utilizes it without including a proof, which will take a little more space than what Sepehr did.