Torben, I noticed something along those lines long ago: the first non-prime
Mersenne number is M11 which factors to 23 times 89. The very next non-prime
Mersenne number is M23, and M89 is also not prime. It occurred to me then
that possibly Mx is never prime if x is a factor of a Mersenne number,
M89 is prime! M89 = 618.970.019.642.690.137.449.562.111 with no known
factors.
So it would be lovely if we could rule out any possible Mx if x had
earlier been a factor for any other My. :-) But no.
M11 proves this so nicely: M23 has factors, M89 none.
I've started looking for some factors,
Steve Harris claimed that M89 is not prime, but it is! So his
conjecture about being able to eliminate a few Mersenne candidates
because the exponent is a factor of a non-prime Mersenne number won't
work.
Phil Moore
_
Jeroen wrote:
to find the value v where prime p is a factor of 2^v-1
tempvalue = p
count = 0
while tempvalue != 0
{
if tempvalue is odd
{
shiftright tempvalue
count++
}
else
{
tempvalue+=p
}
} ...
(Uh, did you swap your 'if' and 'else' clauses? if temp is
danny fleming [EMAIL PROTECTED] wrote:
To Whom It May Concern:
I have devised a method of easily figuring out
approximately how many prime numbers are before
a given prime. Here it is: since the natural
logarithm of a number increases +2.3 for every
power of 10, the 39th Mersenne
Bruce Leenstra wrote:
As luck would have it, this is nearly what I am doing right now:
tempvalue = (q+1)/2
count = 1
while tempvalue != 1 {
if tempvalue is odd tempvalue += q
shiftright tempvalue
count++
}
v = count
I'm not sure I understand that code yet, but
I've
