64/49 |6 0 0 -2>
462.3482 cents
The septatonic? major third, 64/49, is equal to two supermajor seconds of 8/7, and is the interval between 21/16 and 12/7. it is 1029/1024 flat of 21/16, and tempering out 1029/1024 leads to slendric temperament, where three supermajor seconds make up a fifth.