Type in a positive integer N and push the button "Go". The result is a list of the first 100 terms of the so-called Collatz-, Syracuse-, or 3n+1-sequence starting with your given N. For a more extensive description and a list of record calculations we refer to Eric Roosendaal's 3n+1-homepage.

If you want to see the 100-th to the 200-th term of the
Collatz-sequence, type these
values in the fields preceded by "Show from" and "to".

At the lower right end you find a menu where you can decide to show the numbers in ordinary decimal numbers, or in the binary number system.

You may want to know what happens if you change 3n+1 into 3n-1, or 5n-1, or something else. This can be effected by making a choice in the menu called "Method".

After the menu "Method" you find a second menu with the items "long" and "short". The "long" method simply carries out the Collatz-algorithm n->n/2 if n is even and n->3n+1 if n is odd. The "short" version immediately carries out a division by 2 after the n->3n+1 step. So the short version reads n->n/2 if n even and n->(3n+1)/2 if n is odd. The same principle applies to the 3n-1, 5n-1, etc. method.

Author: Frits Beukers, February 2002