fak func

main.go

‎‎​package main

import (
	"fmt"
	"os"
	"strconv"
)

func fak(n int) int {
	if n == 1 {
		return n
	}

	return n + fak(n-1)
}

func main() {
	if len(os.Args) < 2 {
		os.Exit(1)
	}

	n, _ := strconv.Atoi(os.Args[1])
	fmt.Printf("%d: %d\n", n, fak(n))
}