seed(3571).		/* set seed value to a large prime number */

random(R, N) :-
  seed(S),
  N is (S mod R),	/* use seed to generate random number in range */
  retract(seed(S)),	/* delete seed fact */
  NewSeed is (125 * S + 1) mod 4096,	/* compute new seed */
  asserta(seed(NewSeed)), 	/* add new seed fact */
  !.			/* do not backtrack */