Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Challenges

Comments on Ratio limits of fibonacci-like series

Parent

Ratio limits of fibonacci-like series

+5
−0

Definition

$F_{n}\left(0\right)=0$

$F_{n}\left(1\right)=1$

$F_{n}\left(x\right)=n\cdot F_{n}\left(x-1\right)+F_{n}\left(x-2\right)$

For example:

$F_{1}=\left[0,1,1,2,3,5,8,13,21,34,55,89...\right]$

$F_{2}=\left[0,1,2,5,12,29,70,169,408,985...\right]$

$F_{3}=\left[0,1,3,10,33,109,360,1189,3927...\right]$

Challenge

Given n, find the limit of the ratio between consecutive terms, correct to at least the first 5 decimal places.

Test Cases

1 -> 1.61803...
2 -> 2.41421...
3 -> 3.30277...
4 -> 4.23606...

Scoring

This is code-golf. Shortest answer in each language wins.

History
Why does this post require attention from curators or moderators?
You might want to add some details to your flag.
Why should this post be closed?

0 comment threads

Post
+3
−0

JavaScript (Node.js), 27 22 bytes

-5 bytes thanks to Hakerh400‭

Direct computation

f=n=>(n+(n*n+4)**.5)/2

$$\frac{n+\sqrt{n^2+4}}{2}$$

Try it online!

History
Why does this post require attention from curators or moderators?
You might want to add some details to your flag.

1 comment thread

General comments (4 comments)
General comments
rak1507‭ wrote almost 4 years ago

Nice, interested in how you figured out the explicit formula.

Moshi‭ wrote almost 4 years ago

@rak1507 lol, does "looking it up" count as an answer to that question? You can derive it pretty easily though by simply assuming that it converges to $F_n(x+1)=rF_n(x)$ (where r is the ratio we want) and plugging it into recurrence equation.

Hakerh400‭ wrote almost 4 years ago

Math.sqrt -> **.5

Moshi‭ wrote almost 4 years ago

@Hakerh400 Thanks!