CREATE TABLE table_30173 ("No. in series" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" FLOAT)

What number in series was the episode written by Eric Gilliland?
SELECT MAX("No. in series") FROM table_30173 WHERE "Written by" = 'Eric Gilliland'
SELECT MAX("No. in series") FROM "table_30173" WHERE "Written by" = 'Eric Gilliland'