SELECT SUM("Attendance") FROM table_71605 WHERE "H / A" = 'n'
What is the sum of attendance for H/A values of 'n'?
CREATE TABLE table_71605 (
    "Date" text,
    "Round" text,
    "Opponents" text,
    "H / A" text,
    "Result F\u2013A" text,
    "Attendance" real
)