fibonaccib(0,1).
fibonaccib(1,1).
fibonaccib(X,Y) :- A is X-1,
                   B is X-2,
                   fibonaccib(A,A2),
                   fibonaccib(B,B2),
                   Y is A2+B2,
                   asserta(fibonaccib(X,Y)).

fibonacci(0,1).
fibonacci(1,1).
fibonacci(X,Y) :- fibonaccia(1,1,1,X,Y).

fibonaccia(C,P,T,X,Y) :- C2 is C+1,
                         ( C2<X,
                           P2 is T,
                           T2 is P+T,
                           fibonaccia(C2,P2,T2,X,Y)
                         );
                         Y is P+T.