Mathematicians have discovered another property of primes

View of a giant incandescent light bulb as part of the Incandescence installation by artist Severine Fontaine during the rehearsal for the Festival of Lights in central Lyon late in the night December 4, 2014. The Festival of Lights (Fetes des Lumieres), with designers from all over the world, is one of Lyon's most famous Festivals to date and will run from December 5 to December 8, 2014. Picture taken December 4, 2014.
As well as being divisible only by one and themselves, primes are unlikely to end in the same digit as the previous prime number.Image: REUTERS/Robert Pratta

Two mathematicians have uncovered a simple, previously unnoticed property of prime numbers — those numbers that are divisible only by 1 and themselves. Prime numbers, it seems, have decided preferences about the final digits of the primes that immediately follow them.

Among the first billion prime numbers, for instance, a prime ending in 9 is almost 65 percent more likely to be followed by a prime ending in 1 than another prime ending in 9. In a paper posted online today, Kannan Soundararajan and Robert Lemke Oliver of Stanford University present both numerical and theoretical evidence that prime numbers repel other would-be primes that end in the same digit, and have varied predilections for being followed by primes ending in the other possible final digits.

“We’ve been studying primes for a long time, and no one spotted this before,” said Andrew Granville, a number theorist at the University of Montreal and University College London. “It’s crazy.”

The discovery is the exact opposite of what most mathematicians would have predicted, said Ken Ono, a number theorist at Emory University in Atlanta. When he first heard the news, he said, “I was floored. I thought, ‘For sure, your program’s not working.’”

Read the full article here: https://www.quantamagazine.org/20160313-mathematicians-discover-prime-conspiracy/

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