Here's an alternative for you to consider:
mySum[p_List, iMin_] :=
Tr @ MapIndexed[CenterDot[iMin - 1 + #2[[1]], #] &, p] //
Row[{#, Times @@@ #}, "\[LongEqual]"] &
mySum[1/7 {3, 2, 0, 2}, 0]
Mr.Wizard
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