3n+1 Flying Saucers

starting number n

10

steps

2

The Collatz sequence is built starting from the number

n

. If

n

is even, compute

n

2

; if n is odd, compute

3n+1

. Repeat using the result.

Here these sequences are shown using red spheres for even numbers and blue ones for odd numbers.

Does this process always end? That is still an open problem. It is true for small numbers.