@ @SY@ @óïbÿa@‡ÉÜa@ú†bjà@ @ 4. 3() .(1,2, 3),(2, 3, 4),(3, 4,5),(4,5, 6) 3. 4() .(1,2, 3, 4),(2, 3, 4,5),(3, 4, 5, 6) . 5 () .(1,2, 3, 4, 5),(2, 3, 4, 5,6) . 6 () .(1,2, 3, 4, 5, 6) . 6 + 5 + 4 + 3 + 2 + 1 = 21