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Cassini's Identity

For $F_n$ the $n$th Fibonacci Number,

\begin{displaymath}
F_{n-1}F_{n+1}-{F_n}^2=(-1)^n.
\end{displaymath}

See also Fibonacci Number


References

Petkovsek, M.; Wilf, H. S.; and Zeilberger, D. A=B. Wellesley, MA: A. K. Peters, p. 12, 1996.




© 1996-9 Eric W. Weisstein
1999-05-26