5ado is the arithmetic equal division of the octave into four parts of 1/5 each. As 5 is an odd number, this ADO does not contain a perfect fifth or any reasonable approximation to it.

Intervals

# Cents Ratio Interval name
0 0 1/1 perfect unison
1 315.6 6/5 just minor third
2 582.5 7/5 narrow tritone
3 813.7 8/5 just minor sixth
4 1017.6 9/5 just minor seventh
5 1200.0 2/1 perfect octave