CREATE TABLE table_23449363_1 (leagues_entering_at_this_round VARCHAR2, winners_from_previous_round VARCHAR2)

Which leagues entered in rounds where there were 16 winners from the previous round?
SELECT leagues_entering_at_this_round FROM table_23449363_1 WHERE winners_from_previous_round = "16"
SELECT "leagues_entering_at_this_round" FROM "table_23449363_1" WHERE "16" = "winners_from_previous_round"