>>670

x^2-2x-1=(x-1)^2-2=-2(1-{(x-1)^2}/2)
ゆえ
1/(D^2-2D-1)=(-1/2)*Σ[{(D-1)^2}/2]^n
{1/(D^2-2D-1)}[xe^x] = (-1/2)*Σ[{(D-1)^2}/2]^n [xe^x]