WOLFRAM|DEMONSTRATIONS PROJECT

Density Map for the 3n+1 Problem

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range
10
Start with a number
x
and repeat: if
x
is even, halve it; if
x
is odd, triple it and add one. For example, starting with 3 gives 3, 10, 5, 16, 8, 4, 2, 1. Rearrange the numbers in ascending order and mark those places across row
x
so that the third row has marks at the places 1, 2, 3, 4, 5, 10, 16.