Problem with "arg;" when creating a matrix inside of a data.frame() cell

Question

I'm quite new to R. I've been learning R Studio and been working on R Markdown in HTML format. So I apologize in advance if my code seems chaotic.

...
Variable_List <- data.frame(
...

"Method" = c(
    "$$\\bar{x} = \\frac{\\sum{x_i}}{n}$$ where \"$x_{i}$\" is each individual measurement while \"$n$\" is the number of observations.",
    "$$\\sum_{i=1}^{n}(x_{i}-\\bar{x})^{2}$$",
    "$$SS_{xy} = \\sum_{i=1}^{n}(x_{i}-\\bar{x})(y_{i}-\\bar{y})$$",
    "$$\\sigma_{x} = \\sqrt{\\frac{SS_{x}}{n}}$$",
    "$$s_{x} = \\sqrt{\\frac{SS_{x}}{n-1}}$$",
    "$$\\sigma_{xy} = \\frac{SS_{xy}}{n}$$",
    "$$s_{xy} = \\frac{SS_{xy}}{n-1}$$",
    "$$\\rho_{xy} = \\frac{\\sigma_{xy}}{\\sigma_{x}\\sigma_{y}}$$",
    "$$\\hat{y}(x) = \\alpha + \\beta x$$ Where $\\alpha$ and $\\beta$ are constants. Although there are various methods of finding the constants, one method is through matrix regression.<br>Let ${(x_{i},y_{i})}_{i=1}^{n}$ be a range of measurements for two variables, $x$ and $y$.<br> A matrix X for the independent variable $x$ and a vector $\\overrightarrow{y}$ for the dependent variable $y$ can be defined as such:<br>\\begin{bmatrix}1 & x_{1} \\\\ \\vdots & \\vdots \\\\1 & x_{n} \\end{bmatrix} "

...
),
...

I know, a lot is going on here, but I need help on this bit at the end:

\\begin{bmatrix}1 & x_{1} \\\\ \\vdots & \\vdots \\\\1 & x_{n} \\end{bmatrix}

I tried creating a matrix with the help of atomurl math TeX generator online. I got a matrix going, but apparently there's a new column in between with each row saying "amp;" and I'm confused as to why. I wanted to create a matrix with 2 columns and three rows, where first row has "1" and "x_{1}", second row is a set of \\vdots and last row is "1" and "x_{n}".

Here's a bit of extra code in the same R code block. Could be helpful for anyone who's answering?

Variable_List <- data.frame(Variable_List2, row.names = NULL)
kable(Variable_List, format = "html", escape = TRUE, row.names = FALSE, caption = "Table 1.2.1: Variable List") %>%
  kable_styling(
    bootstrap_options = c("striped"),
    full_width = FALSE,
    position = "center"
  ) %>%
  column_spec(1, border_left = "2px solid #ddd") %>%
  column_spec(2, border_left = "2px solid #ddd", border_right = "2px solid #ddd") %>%
  column_spec(4, border_left = "2px solid #ddd", border_right = "2px solid #ddd")

I tried adding "\" in front, it gave me an error: " ! '\&' is an unrecognized escape in character string (:49:8) " I tried writing "&&" instead, it just added an extra column with another "amp;" in each row. I tried writing "&" instead, same output where there's a column of "amp;"'s.

I'm lost.