Hmmm....there oughta' be way w/ accumarray in one go, but doesn't come to me at the moment how to work around the restriction (which never have understood need for) that the accumulating values must be only a vector...
1100 2 49 10 61 13 68
1600 1 5 6 8 6 2
1800 3 8 35 82 15 22
or, if a table is good enough for output, can dispense with the table2array conversion back...
For dynamic case, you'll need to build the grouping variable (here 'A6') from the size something like