#let title(cont, size: 18pt) = align(center)[
  #text(size: size * 2, weight: "bold")[#underline[#cont]]
]

#let butcher(s, nums) = {
  let nums = nums.map(x => if type(x) == float or type(x) == int {
    $#x$
  } else { x })
  table(
    stroke: (x, y) => if x == 0 and y == s {
      (right: 0.7pt + black, top: 0.7pt + black)
    } else if x == 0 {
      (right: 0.7pt + black)
    } else if y == s {
      (top: 0.7pt + black)
    },
    align: (x, y) => (
      if x > 0 { center } else { left }
    ),
    columns: s + 1,
    $0$, ..range(s).map(x => none), // first row
    ..range(2, s + 1)
      .map(i => {
        let p(i) = calc.floor(i * i / 2 + i / 2 - 1)
        (
          nums.slice(p(i - 1), p(i - 1) + i),
          range(i, s + 1).map(x => none),
        ).flatten()
      })
      .flatten(),
    none, ..nums.rev().slice(0, s).rev() // last row
  )
}