Find the sum to infinity of the series

1 + 4/3! + 6/4! + 8/5!

2 answers

The book says the a answer is 2
sum[1,∞] 2n/(n+1)!
= 2 sum[1,∞] n/(n+1)!
= 2 sum[1,∞] (n+1-1)/(n+1)!
can you take it from there?