How many different values of clubs involved were there when the league entering at this round was allsvenskan?
CREATE TABLE "teams" (
  "round" text,
  "clubs_remaining" real,
  "clubs_involved" real,
  "winners_from_previous_round" real,
  "new_entries_this_round" text,
  "leagues_entering_at_this_round" text
);
SELECT COUNT("clubs_involved") FROM "teams" WHERE "leagues_entering_at_this_round"='Allsvenskan';