The focus of the parabola $y ^ { 2 } = 4 x + 16$ is the centre of the circle $C$ of radius 5. If the values of $\lambda$, for which $C$ passes through the point of intersection of the lines $3 x - y = 0$ and $x + \lambda y = 4$, are $\lambda _ { 1 }$ and $\lambda _ { 2 }$, $\lambda _ { 1 } < \lambda _ { 2 }$, then $12 \lambda _ { 1 } + 29 \lambda _ { 2 }$ is equal to