Question 804441
<pre>
That's the Fibonacci sequence

1,1,2,3,5...

You start off with the first two terms being 1.

To get the next number you add the two preceding numbers

Binet's formula for the nth Fibonacci number is

Fib(n) = {{{1/sqrt(5)}}}{{{(matrix(3,3,

   "", "", "",
((1+sqrt(5))/2)^n,""-"",((1-sqrt(5))/2)^n,
"", "", ""))}}}

Fib(50) = {{{1/sqrt(5)}}}{{{(matrix(3,3,

   "", "", "",
((1+sqrt(5))/2)^50,""-"",((1-sqrt(5))/2)^50,
"", "", ""))}}} = 12586269025

Edwin</pre>