Skip to content

Sunday Times Teaser 2607 – Tribonacci

by H Bradley and C Higgins

Published: 9 September 2012 (link)

I have been experimenting with sequences of numbers in which each number after the third is the sum of the previous three numbers.

My first three numbers are always different positive whole numbers in increasing order.

I have found such a sequence in which only the first five numbers are below 100 and for which 10000 occurs later in the sequence.

What are my first three numbers?

3 Comments Leave one →
  1. brian gladman permalink

    Here is my solution:

  2. Trevor Kirsten permalink

    Hi Brian,
    I agree with your values for A<19 & B<25 but for the sake of completeness it should be C<48.
    e.g. 1,2,47,50,99,196, …
    It doesn't change the answer but does test for many more possible sequences!

    • Brian Gladman permalink

      You are right, of course. I have just looked at my code for this teaser and I have found that I had posted the wrong code, which I have corrected now. Thanks for spotting the issue and hence prompting an update.

Leave a Reply

Note: HTML is allowed. Your email address will not be published.

Subscribe to this comment feed via RSS