Latex Formulas or symbols in table cells using kni

Thanks to jaySf I was able to create a pdf file containing beautiful tables with footnotes showing formulas and symbols with R Markdown, Latex, knitr and kableExtra (below his example):

---
title: "Untitled"
output: pdf_document
---

```{r tab}
library(knitr)
library(kableExtra)
df <- data.frame(v1=rnorm(6), v2=runif(6), v3=rbinom(6, 1, .33), 
             row.names=LETTERS[1:6])
kable(df, "latex", align="c", booktabs=TRUE) %>%
footnote(general=c("$a^2+b^2=c^2,$",     
                   "$\\\\sigma^2=\\\\frac{1}{n-1}\\\\sum_{i=1}^n(x_i-\\\\bar{x})^2;$", 
                   "1,000 \\\\$;", "100\\\\%."),
         number=c("Hello\ there! \\\\textit{Hello\ there!}"),
         footnote_as_chunk=TRUE, 
         escape=FALSE)
```

which results in:

Now I'm struggling with putting symbols or formulas within one of the actual cells of the table. Could someone make an example which shows regular text and symbols and formulas within one cell? Preferably also the same in table title, in one of the column names and one in one the row names of the table and with some numbered footnotes referring to information in one of the cells or title or col or row names, I'm dying for an example which has it all! Many many thanks.

Sure: take note of the argument escape passed to kable:

---
title: "Untitled"
output: pdf_document
---

```{r tab}
library(knitr)
library(kableExtra)
df <- data.frame(v1=rnorm(6), v2=runif(6), v3=rbinom(6, 1, .33), 
             row.names=LETTERS[1:6])

df$v4 <- c('My formula $\\sum_{i=1}^9$')
kable(df, "latex", align="c", booktabs=TRUE, escape = F, caption = '$\\Gamma$') %>%
footnote(general=c("$a^2+b^2=c^2,$",     
                   "$\\\\sigma^2=\\\\frac{1}{n-1}\\\\sum_{i=1}^n(x_i-\\\\bar{x})^2;$", 
                   "1,000 \\\\$;", "100\\\\%."),
         number=c("Hello\ there! \\\\textit{Hello\ there!}"),
         footnote_as_chunk=TRUE, 
         escape=FALSE)
```

Another example with italic column names and an additional header:

```{r, echo = F}
library(knitr)
library(kableExtra)
df <- data.frame(v1=rnorm(6), v2=runif(6), v3=rbinom(6, 1, .33), 
             row.names=LETTERS[1:6])
df$v4 <- c('My formula $\\sum_{i=1}^9$')

# italic column headers
colnames(df) <- paste0("\\textit{", colnames(df),"}")

kable(df, "latex", align="c", booktabs=TRUE, escape = F, caption = '$\\Gamma$') %>%
footnote(general=c("$a^2+b^2=c^2,$",     
                   "$\\\\sigma^2=\\\\frac{1}{n-1}\\\\sum_{i=1}^n(x_i-\\\\bar{x})^2;$", 
                   "1,000 \\\\$;", "100\\\\%."),
         number=c("Hello\ there! \\\\textit{Hello\ there!}"),
         footnote_as_chunk=TRUE, 
         escape=FALSE) %>%
  add_header_above(header = c("\\\\textbf{Results} $\\\\Delta$" = 5), escape = F)
```