local int = require "int"
local fmt = require "fmt"
require "table2"

local function successive_primes(primes, diffs)
    local results = {}
    local dl = #diffs
    for i = 1, #primes - dl do
        local group = table.rep(dl + 1, 0)
        group[1] = primes[i]
        for j = i, i + dl - 1 do
            if primes[j + 1] - primes[j] != diffs[j - i + 1] then
                continue 2
            end
            group[j - i + 2] = primes[j + 1]
        end
        results:insert(group)
    end
    return results
end

local primes = int.primes(999_999)
local diffs_list = { {2}, {1}, {2, 2}, {2, 4}, {4, 2}, {6, 4, 2} }
print("For primes less than 1,000,000:-\n")
for diffs_list as diffs do
    print($"  For differences of {fmt.swrite(diffs)} ->")
    local sp = successive_primes(primes, diffs)
    if #sp == 0 then
        print("    No groups found\n")
        continue
    end
    print($"    First group   =  {fmt.swrite(sp[1])}")
    print($"    Last group    =  {fmt.swrite(sp[#sp])}")
    print($"    Number found  =  {#sp}\n")
end