[QUOTE=storm5510;187338]

The second line was sort of a jaw-dropper, meaning it hit me right off. Any binary number consisting of all 1's is Mersenne.

[/QUOTE]

False. Any binary repunit with a [b]prime[/b] number of bits is Mersenne.

[QUOTE=R.D. Silverman;187385]False. Any binary repunit with a [b]prime[/b] number of bits is Mersenne.[/QUOTE]

According to Wikipedia, both definitions are used:

[quote=Wikipedia]In mathematics, a Mersenne number is a positive integer that is one less than a power of two. Some definitions of Mersenne numbers require that the exponent n be prime.[/quote]

[QUOTE]False. Any binary repunit with a [B]prime[/B] number of bits is Mersenne. [/QUOTE]

depend on how you define a mersenne number,id define it as 2^n-1,where n is any positive integer.