%Create a list of prime numbers

%divisible(X,Y):- Y=<X,X mod Y =:= 0.
%divisble(X,Y):- Y < X, Y1 is Y + 1, divisible(X,Y1).

%divisible(10,2).
divisible(X,Y):- N is Y*Y,N =< X,X mod Y =:= 0.
divisible(X,Y):- Y < X, Y1 is Y + 1, divisible(X,Y1).

%isprime([3],Z).
isprime([X|_],X):-Y is 2, X >1, \+divisible(X,Y).
isprime([_|T],Z):-isprime(T,Z).

%put into a list of N numeros.
%genList(10,L).
genList(0,[]).
genList(N,[X|Xs]):- N > 0,
                    X is N+1,
                    N1 is N-1,genList(N1,Xs).

%calculate prime numbers until N
%ie lstPrimes(20,C).
lstPrimes(N,C):-genList(N,X),isprime(X,C).