Odd time signatures

The time signature (also known as meter signature,metre signature, or measure signature) is a notational convention used in Western musical notation to specify how many beats (pulses) are to be contained in each measure (bar) and which note value is equivalent to one beat.

In a music score, the time signature appears at the beginning, as a time symbol or stacked numerals, such as or ³
₄ (read common time and three-four time, respectively), immediately following the key signature or immediately following the clef symbol if the key signature is empty. A mid-score time signature, usually immediately following a barline, indicates a change of meter.

There are various types of time signatures, depending on whether the music follows simple rhythms or involves unusual shifting tempos, including: simple (such as 3
4 or 4
4), compound (e.g., 9
8 or 12
8), complex (e.g., 5
4 or 7
8), mixed (e.g., 5
8 & 3
8 or 6
8 & 3
4), additive (e.g., 3+2+3
8), fractional (e.g., ​2 1⁄2
4), and irrational meters (e.g., 3
10 or 5
24).

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Wikipedia