1 ((-2*(-1 + Sqrt[1 + k^2/(c - I*k0)^2])*(c - I*k0))/k + ((-1 + Sqrt[1 + k^2/(2*c - I*k0)^2])*(2*c - I*k0))/k + (Sqrt[Pi]*(Piecewise[{{0, k^2/k0^2 <= 1}}, (2*Sqrt[k^2 - k0^2])/(k*Sqrt[Pi])] + I*Piecewise[{{(2*k0)/(k*Sqrt[Pi]), k0^2/k^2 < 1}, {(2*(k0 - Sqrt[-k^2 + k0^2]))/(k*Sqrt[Pi]), k0^2/k^2 > 1}}, 0]))/2)/k0^2
2 Piecewise[{{SeriesData[k, Infinity, {c^2/k0^2, 0, (3*c^2)/2 - (7*c^4)/(4*k0^2) + ((3*I)*c^3)/k0, 0, (31*c^6 - (90*I)*c^5*k0 - 105*c^4*k0^2 + (60*I)*c^3*k0^3 + 15*c^2*k0^4)/(8*k0^2), 0, (-5*(127*c^8 - (504*I)*c^7*k0 - 868*c^6*k0^2 + (840*I)*c^5*k0^3 + 490*c^4*k0^4 - (168*I)*c^3*k0^5 - 28*c^2*k0^6))/(64*k0^2), 0, (7*(511*c^10 - (2550*I)*c^9*k0 - 5715*c^8*k0^2 + (7560*I)*c^7*k0^3 + 6510*c^6*k0^4 - (3780*I)*c^5*k0^5 - 1470*c^4*k0^6 + (360*I)*c^3*k0^7 + 45*c^2*k0^8))/(128*k0^2)}, 2, 11, 1], (k0 <= 0 && k^2/k0^2 > 1) || k0 > 0}}, SeriesData[k, Infinity, {-k0^(-2), 0, (2*c^2 + k0^2)/(2*k0^2), 0, ((c*(c - I*k0)^3)/4 - (c*(2*c - I*k0)^3)/4 - I/4*(c - I*k0)^3*k0 + I/8*(2*c - I*k0)^3*k0)/k0^2, 0, (-(c*(c - I*k0)^5)/8 + (c*(2*c - I*k0)^5)/8 + I/8*(c - I*k0)^5*k0 - I/16*(2*c - I*k0)^5*k0)/k0^2, 0, ((5*c*(c - I*k0)^7)/64 - (5*c*(2*c - I*k0)^7)/64 - (5*I)/64*(c - I*k0)^7*k0 + (5*I)/128*(2*c - I*k0)^7*k0)/k0^2, 0, ((-7*c*(c - I*k0)^9)/128 + (7*c*(2*c - I*k0)^9)/128 + (7*I)/128*(c - I*k0)^9*k0 - (7*I)/256*(2*c - I*k0)^9*k0)/k0^2}, 0, 11, 1]]