Mersenne Number whose Index is Mersenne Prime/Historical Note

Historical Note on Mersenne Number whose Index is Mersenne Prime
The composite nature of $2^{8191} - 1$ was reported on by in $1954$, in an article in the :


 * The corresponding Mersenne number was actually tested in $1953$ by D.J. Wheeler on the Illiac, at the University of Illinois, one hundred hours of machine time being required.