CREATE TABLE table_21629 ("Series #" FLOAT, "Season #" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT)

Which seasons were directed by Nelson McCormick?
SELECT "Title" FROM table_21629 WHERE "Directed by" = 'Nelson McCormick'
SELECT "Title" FROM "table_21629" WHERE "Directed by" = 'Nelson McCormick'