ciag_aryt(L1) :- L1=[A,B],!.
ciag_aryt(L1) :-L1=[A,B,C], C-B =:= B-A,!.
ciag_aryt(L1) :-
     L1=[A,B,C|T],
       C-B =:= B-A,

    ciag_aryt([B,C|T]).

odleglosc(L1,W) :- ciag_aryt(L1), L1=[A,B|T], W is B-A.


stw_ciag(L1,I,L2) :-  ciag_aryt(L1), odleglosc(L1,R), ciag(L1,I,R,L2).




ciag(L1,I,R,L2) :- I=:=0, L2=L1,!.
ciag(L1,I,R,L2) :- append(T,[H],L1), A is H+R, append(L1,[A],LW1),
    I1 is I-1,
    ciag(LW1,I1,R,L2).