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[✓] Increment in multiple sum indices?

GROUPS:

Hello, I am trying to write nested sums of the following form:

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But i need the index j to run from 0 with an increment as follows:

enter image description here

any suggestions? Thanks

POSTED BY: Shahzeb Kamal
Answer
11 days ago

You can use Fold:

With[{k = 2},
 Fold[Sum[#1, {Subscript[a, #2], 0, n}] &, Sum[a[i] x^i, {i, 0, n}], 
  Range[0, k]]]
POSTED BY: Gianluca Gorni
Answer
11 days ago

Thanks :) Solved!

POSTED BY: Shahzeb Kamal
Answer
11 days ago

Group Abstract Group Abstract