Let's have the sequence 26,135,701,3640,

What are the first two terms of this sequence and what number follows 3640?

  • 1
    $\begingroup$ This sequence is in the OEIS: oeis.org/A052918. $\endgroup$ Aug 17, 2020 at 4:37
  • $\begingroup$ Haha I wished I googled it, it would have saved me alot of effort $\endgroup$
    – PDT
    Aug 17, 2020 at 6:17
  • $\begingroup$ This sequence derives from continuous fractions and expresses an arithmetical value of the algebraic number: (the square root of 29 minus 5) over two. I didn't know it is on OEIS.. $\endgroup$ Aug 17, 2020 at 6:29

1 Answer 1


The answer is before 1,5 after 18901

Explanation: Basically take a number multiply it by 5 and add the previous number to it.

  • 2
    $\begingroup$ I'm sure that's the right answer, but I'm having a hard time understanding why. Could you maybe add an explanation? $\endgroup$
    – Chipster
    Aug 17, 2020 at 2:23
  • $\begingroup$ Basically take a number multiply it by 5 and add the previous number to it $\endgroup$
    – PDT
    Aug 17, 2020 at 4:00
  • $\begingroup$ Its an easy one imo $\endgroup$
    – PDT
    Aug 17, 2020 at 4:01
  • $\begingroup$ Perhaps I'm just really bad at seeing patterns like that. Anyway, thanks for the explanation. $\endgroup$
    – Chipster
    Aug 17, 2020 at 5:33
  • $\begingroup$ Basically stumbled across it by seeing that the previous number of each number was roughly 5 times larger and when I punched in one of the numbers times 5 on a calculator I saw that the difference between the next number for one of them was the previous number and then I tried this for all and I saw the pattern $\endgroup$
    – PDT
    Aug 17, 2020 at 6:22

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