CREATE TABLE table_19768 ("Week" FLOAT, "Date" CLOB, "Opponent" CLOB, "Result" CLOB, "Record" CLOB, "Game Site" CLOB, "Attendance" FLOAT)

Name the number of weeks for san francisco 49ers
SELECT COUNT("Week") FROM table_19768 WHERE "Opponent" = 'San Francisco 49ers'
SELECT COUNT("Week") FROM "table_19768" WHERE "Opponent" = 'San Francisco 49ers'