#!/bin/bash
color() {
  for c; do
    printf '\e[48;5;%dm%03d' $c $c
  done
  printf '\e[0m \n'
}

IFS=$' \t\n'
color {0..15}
for ((i = 0; i < 6; i++)); do
  color $(seq $((i * 36 + 16)) $((i * 36 + 51)))
done
color {232..255}