How two outsiders tackled the mystery of arithmetic progressions
Computer scientists made progress on a decades-old math puzzle that asks where order exists
The primes contain infinitely many arithmetic progressions, including the five-term progression 5, 11, 17, 23, 29.
Lisa Sheehan
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.”
Yet for almost a century, mathematicians in the field of combinatorics have been puzzling out how to know whether an endless list of numbers contains such a sequence, called an arithmetic progression.