2^9689-1 is prime!

This was first "proved" by computer in 1963. There has been controvercy since

the 4 color theorem was allegedly proved with use of a computer. Many

mathematicians still refuse to accept computer proofs. To their satisfaction,

2^9689-1 is now the largest prime which has been verified manually. It has not

been verified whether it is the 21st Mersenne prime.

The computation was performed by 100000 pupils in Danish schools and completed

today.

The project was proposed and organized by math students. The purpose was to make

pupils train pen-and-paper calculations, plus make them interested in

collaboration and mathematics.

Computers (yes, the darn things) were originally used to split the Lucas-Lehmer

test using DWT FFT into millions of subtasks which could then be verified in

parallel. Every subtask was performed by two independent pupils not knowing the

computer result. When results did not match, a third computation was performed.

High school and math students verified manually that all the subtasks really did

amount to a primality proof.

The 1/4 million sheets of handwritten calculations will be used to form

"2^9689-1" on a 1/4 km^2 field photographed from space.

--

Jens Kruse Andersen