Com numeração especial:
40
1_2, 3_4, 5_6, 7_8, 9_10, 11_12, 13_14, 15_16, 17_18, 19_20, 21_22, 23_24, 25_26, 27_28, 29_30, 31_32, 33_34, 35_36, 37_38, 39_40, 41_42, 43_44, 45_46, 47_48, 49_50, 51_52, 53_54, 55_56, 57_58, 59_60, 61_62, 63_64, 65_66, 67_68, 69_70, 71_72, 73_74, 75_76, 77_78, 79_80