Interesting. Reminds me of the “snake oil” technique useful when evaluating complex sums in combinatorics. By treating the sum in question as the coefficient of

Interesting. Reminds me of the “snake oil” technique useful when evaluating complex sums in combinatorics. By treating the sum in question as the coefficient of x^n in another sum, you can often obtain an expression where finding the coefficient of x^n — which is the value you’re after — is simple.