How to write exponential of subscript in Mathematica?

What kind of answer did you expect? I would write

Subscript[u, 1][i_, j_] := (u[i, j + 1] + u[i, j])/2;
Exp[Subscript[u, 1][i, j]]

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int = Integrate[1/(x^3 - 1), x];
Map[Framed, int, Infinity]

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