Problem #375
Sigma Sigma Sigma Boy
Let f(i) denote the i^{th} Fibonacci number (f(0)=0,f(1)=1). Based on the given definition, find the value of S(1234567) modulo 1,000,000,007.
S(n)=\sum_{i=1}^{n} \sum_{j=0}^{i - 1} \sum_{k=j + 1}^{i} f(i) \cdot f(j) \cdot f(k)