The given series is a geometric series. We can rewrite the series as
∑k=1∞(πe)k+1=∑k=1∞(πe)(πe)k=πe∑k=1∞(πe)k. The sum of an infinite geometric series ∑k=1∞ark−1 is 1−ra if ∣r∣<1. Alternatively, we can write ∑k=1∞rk=1−rr if ∣r∣<1. In our case, we have ∑k=1∞(πe)k. Here, r=πe. Since e≈2.718 and π≈3.141, we have πe<1. Thus, the series converges. Using the formula for the sum of an infinite geometric series, we have
∑k=1∞(πe)k=1−πeπe=ππ−eπe=π−ee. Therefore, the sum of the given series is
πe∑k=1∞(πe)k=πe⋅π−ee=π(π−e)e2.