key => value
0 => 0
1 => 10
2 => 20
3 => 30
4 => 40

---

key => value: product
0 => 0: 0 * 2 = 0
1 => 10: 10 * 2 = 20
2 => 20: 20 * 2 = 40
3 => 30: 30 * 2 = 60
4 => 40: 40 * 2 = 80

---

key => value: product + summand
0 => 0: 0 * 17 + 1 = 1
1 => 10: 10 * 17 + 1 = 171
2 => 20: 20 * 17 + 1 = 341
3 => 30: 30 * 17 + 1 = 511
4 => 40: 40 * 17 + 1 = 681