Named for Marin Mersenne (1588-1648), French mathematician and philosopher, best known for his discovery of prime numbers of the form 2ⁿ-1 and that n is then necessarily also prime. The number 8191 = 2¹³-1 is the fifth Mersenne prime. Mersenne correctly verified that the numbers are prime also for n = 17, 19 and 31---and that they are not prime for n = 11, 23 and 29. The largest prime Mersenne correctly established was for n = 127. Name proposed by the discoverer, following a suggestion by B. G. Marsden, who wrote the citation.