Why Mathematica couldn't perform the series:
Normal[FullSimplify[Series[-(-1)^(n + k)*Sin[Pi*\[Lambda]]/Pi
*Gamma[\[Lambda], 0, 1], {\[Lambda], 0, 1}]]]
and just give the incomplete answer
(-1)^(k + n) \[Lambda] Gamma[0, 1] + (-1)^(
1 + k + n) \[Lambda] Gamma[\[Lambda], 0]
The difficulty is the indeterminate problem. How to circumvent the issue? Thanks.