Heya! Is there any way to get Mathematica to simplify this (i.imgur.com/WEKlDOQ.png) type of Method of Frobenius work more? I was expecting Simplify[] to do the index shifting to get a single summation.
Curiously I get a much higher Benchmark result with 12.3 than the prerelease, 5.653 on 12.3 and 4.917 on the prerelease. Maybe it's compiled with -O0 instead of -O3 :)