Recurrence relation challenges

$\textbf{Problem 1.}$ Each unit square of a $2$ x $n$ unit squae grid is to be colored blue or red such that no $2$ x $2$ red colored square is obtained.Let $c_n$ denote the number of such colorings.Determine the greatest value of $k$ such that $3^{k} | c_{2001}$ .

$\textbf{Problem 2.}$ For any positive integer $n$ ,p.t,the number of positive integers using only the digits $1,3,4$ whose digit sum is $2n$ is a perfect square.

$\textbf{Problem 3.}$ A fair coin is tossed $10$ times .What is the probability that heads never occur in consecutive tosses.

These problems are not original and are adapted from "A Path to Combinatorics for undergraduates" by Titu Andreescu and Zuming Feng.Post the solutions in the comments!!

#Combinatorics #RecurrenceRelations #Goldbach'sConjurersGroup #TorqueGroup #IntroduceYourself

Easy Math Editor

This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.

When posting on Brilliant:

Use the emojis to react to an explanation, whether you're congratulating a job well done , or just really confused .
Ask specific questions about the challenge or the steps in somebody's explanation. Well-posed questions can add a lot to the discussion, but posting "I don't understand!" doesn't help anyone.
Try to contribute something new to the discussion, whether it is an extension, generalization or other idea related to the challenge.
Stay on topic — we're all here to learn more about math and science, not to hear about your favorite get-rich-quick scheme or current world events.

Markdown	Appears as
`italics` or `_italics_`	italics
`bold` or `__bold__`	bold
- bulleted - list	bulleted list
1. numbered 2. list	numbered list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1 paragraph 2	paragraph 1 paragraph 2
`[example link](https://brilliant.org)`	example link
`> This is a quote`	This is a quote
# I indented these lines # 4 spaces, and now they show # up as a code block. print "hello world"	# I indented these lines # 4 spaces, and now they show # up as a code block. print "hello world"

Math	Appears as
Remember to wrap math in `$` ... `$` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$

Comments

For the first one, I think the relation is such:

$c_{n+1}=4c_n-c_{n-1}$ , where $c_0=1,c_1=4$ .

Am I right?

Bogdan Simeonov - 7 years ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$