Evaluate Series: sin(pi)(sq. rt. (n^2+k^2))

[A00446849]

Homework Statement

sigma n=1 to infinity
sin(pi)(sq. rt. (n^2 + k^2))

Homework Equations

The Attempt at a Solution

 

[Feynman diagram]

Have you made any attempt at a solution? Moreover, have you typed that equation in correctly? (The sine of pi = 0, so the whole series as displayed above will be 0)!