CREATE TABLE table_25038 ("District" TEXT, "Vacator" TEXT, "Reason for change" TEXT, "Successor" TEXT, "Date successor seated" TEXT)

Who left a seat open for the district of connecticut at-large
SELECT "Vacator" FROM table_25038 WHERE "District" = 'Connecticut At-large'
SELECT "Vacator" FROM "table_25038" WHERE "District" = 'Connecticut At-large'