欠けつ番ばん

noun

missing number; vacant number

Refers to a number that is intentionally left out of a sequence, such as a room number, seat number, or item number in a list.

• このホテルには4号ごう室しつがなく、欠けつ番ばんになっている。

  This hotel doesn't have a room 4; it's a missing number.