Infinite sum of reciprocal products
Calculus
Level
3
\[\frac 14 + \frac 2{4 \times 7} + \frac 3{4 \times 7 \times 10} + \frac 4{4 \times 7 \times 10 \times 13} + \cdots = \frac 1a \]
Find \(a\).
\[\]
by
Chew-Seong Cheong