CREATE TABLE table_28884 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" TEXT, "Result" TEXT, "Candidates" TEXT)

Who were the candidates for election that had a result of a retired jacksonian gain?
SELECT "Candidates" FROM table_28884 WHERE "Result" = 'Retired Jacksonian gain'
SELECT "Candidates" FROM "table_28884" WHERE "Result" = 'Retired Jacksonian gain'