# §8.15 Sums

 8.15.1 $\mathop{\gamma\/}\nolimits\!\left(a,\lambda x\right)=\lambda^{a}\sum_{k=0}^{% \infty}\mathop{\gamma\/}\nolimits\!\left(a+k,x\right)\frac{(1-\lambda)^{k}}{k!}.$

For sums of infinite series whose terms include incomplete gamma functions, see Prudnikov et al. (1986b, §5.2).