# Sequences: terms before and after

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

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

• This sequence is in the OEIS: oeis.org/A052918. Commented Aug 17, 2020 at 4:37
• Haha I wished I googled it, it would have saved me alot of effort
– PDT
Commented Aug 17, 2020 at 6:17
• 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.. Commented Aug 17, 2020 at 6:29

The answer is before 1,5 after 18901

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

• I'm sure that's the right answer, but I'm having a hard time understanding why. Could you maybe add an explanation? Commented Aug 17, 2020 at 2:23
• Basically take a number multiply it by 5 and add the previous number to it
– PDT
Commented Aug 17, 2020 at 4:00
• Its an easy one imo
– PDT
Commented Aug 17, 2020 at 4:01
• Perhaps I'm just really bad at seeing patterns like that. Anyway, thanks for the explanation. Commented Aug 17, 2020 at 5:33
• 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
– PDT
Commented Aug 17, 2020 at 6:22