Question 60
Determine the least real number $L$ such that
$$
\frac{1}{a} + \frac{a}{b} + \frac{b}{c} + \frac{c}{d} \leqslant L
$$
for all quadruples $(a, b, c, d)$ of integers satisfying $1 \lt a \lt b \lt c \lt d$.
$$
\frac{1}{a} + \frac{a}{b} + \frac{b}{c} + \frac{c}{d} \leqslant L
$$
for all quadruples $(a, b, c, d)$ of integers satisfying $1 \lt a \lt b \lt c \lt d$.