This website is a semi-functional mirror of the original Project Euler. More information is available on GitHub.
GCD sequence
Problem 443
Published on 02 November 2013 at 04:00 pm [Server Time]
Let g(n) be a sequence defined as follows:
g(4) = 13,
g(n) = g(n-1) + gcd(n, g(n-1)) for n > 4.
The first few values are:
| n | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | ... |
| g(n) | 13 | 14 | 16 | 17 | 18 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 51 | 54 | 55 | 60 | ... |
You are given that g(1 000) = 2524 and g(1 000 000) = 2624152.
Find g(1015).
Go to back to Problems