Math

How two outsiders tackled the mystery of arithmetic progressions

Computer scientists made progress on a decades-old math puzzle that asks where order exists

An image of grey numbers piled on top of each other. All numbers are grey except for the visible prime numbers of 5, 11, 17, 23 and 29, which are highlighted blue.

The primes contain infinitely many arithmetic progressions, including the five-term progression 5, 11, 17, 23, 29.

Lisa Sheehan

By Evelyn Lamb

Consider this sequence of numbers: 5, 7, 9. Can you spot the pattern? Here’s another with the same pattern: 15, 19, 23. One more: 232, 235, 238.  

“Three equally spaced things,” says Raghu Meka, a computer scientist at UCLA. “That’s probably the simplest pattern you can imagine.