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ATH · 2008-05-30, 00:30

Question solved.

I found a factor of 2^p-1*(2^p-1) + 1 for p=132049 with gmp-ecm:
194528547122653

So of the 44 known perfect numbers P=2^p-1*(2^p-1), P+1 is only prime for p=2,3,13 and 19.

2008-05-30, 00:30	#9
ATH Einyen Dec 2003 Denmark 101111010111₂ Posts	Question solved. I found a factor of 2^p-1(2^p-1) + 1 for p=132049 with gmp-ecm: 194528547122653 So of the 44 known perfect numbers P=2^p-1(2^p-1), P+1 is only prime for p=2,3,13 and 19. Last fiddled with by ATH on 2008-05-30 at 00:31