# 友誼數

## 例如

${\displaystyle {\tfrac {\sigma (30)}{30}}={\tfrac {1+2+3+5+6+10+15+30}{30}}={\tfrac {72}{30}}={\tfrac {12}{5}}}$
${\displaystyle {\tfrac {\sigma (140)}{140}}={\tfrac {1+2+4+5+7+10+14+20+28+35+70+140}{140}}={\tfrac {336}{140}}={\tfrac {12}{5}}.}$

### 較細嘅n

 n ${\displaystyle \sigma (n)}$ ${\displaystyle {\frac {\sigma (n)}{n}}}$ n ${\displaystyle \sigma (n)}$ ${\displaystyle {\frac {\sigma (n)}{n}}}$ n ${\displaystyle \sigma (n)}$ ${\displaystyle {\frac {\sigma (n)}{n}}}$ n ${\displaystyle \sigma (n)}$ ${\displaystyle {\frac {\sigma (n)}{n}}}$ n ${\displaystyle \sigma (n)}$ ${\displaystyle {\frac {\sigma (n)}{n}}}$ 1 1 1 37 38 38/37 73 74 74/73 109 110 110/109 145 180 36/29 2 3 3/2 38 60 30/19 74 114 57/37 110 216 108/55 146 222 111/73 3 4 4/3 39 56 56/39 75 124 124/75 111 152 152/111 147 228 76/49 4 7 7/4 40 90 9/4 76 140 35/19 112 248 31/14 148 266 133/74 5 6 6/5 41 42 42/41 77 96 96/77 113 114 114/113 149 150 150/149 6 12 2 42 96 16/7 78 168 28/13 114 240 40/19 150 372 62/25 7 8 8/7 43 44 44/43 79 80 80/79 115 144 144/115 151 152 152/151 8 15 15/8 44 84 21/11 80 186 93/40 116 210 105/58 152 300 75/38 9 13 13/9 45 78 26/15 81 121 121/81 117 182 14/9 153 234 26/17 10 18 9/5 46 72 36/23 82 126 63/41 118 180 90/59 154 288 144/77 11 12 12/11 47 48 48/47 83 84 84/83 119 144 144/119 155 192 192/155 12 28 7/3 48 124 31/12 84 224 8/3 120 360 3 156 392 98/39 13 14 14/13 49 57 57/49 85 108 108/85 121 133 133/121 157 158 158/157 14 24 12/7 50 93 93/50 86 132 66/43 122 186 93/61 158 240 120/79 15 24 8/5 51 72 24/17 87 120 40/29 123 168 56/41 159 216 72/53 16 31 31/16 52 98 49/26 88 180 45/22 124 224 56/31 160 378 189/80 17 18 18/17 53 54 54/53 89 90 90/89 125 156 156/125 161 192 192/161 18 39 13/6 54 120 20/9 90 234 13/5 126 312 52/21 162 363 121/54 19 20 20/19 55 72 72/55 91 112 16/13 127 128 128/127 163 164 164/163 20 42 21/10 56 120 15/7 92 168 42/23 128 255 255/128 164 294 147/82 21 32 32/21 57 80 80/57 93 128 128/93 129 176 176/129 165 288 96/55 22 36 18/11 58 90 45/29 94 144 72/47 130 252 126/65 166 252 126/83 23 24 24/23 59 60 60/59 95 120 24/19 131 132 132/131 167 168 168/167 24 60 5/2 60 168 14/5 96 252 21/8 132 336 28/11 168 480 20/7 25 31 31/25 61 62 62/61 97 98 98/97 133 160 160/133 169 183 183/169 26 42 21/13 62 96 48/31 98 171 171/98 134 204 102/67 170 324 162/85 27 40 40/27 63 104 104/63 99 156 52/33 135 240 16/9 171 260 260/171 28 56 2 64 127 127/64 100 217 217/100 136 270 135/68 172 308 77/43 29 30 30/29 65 84 84/65 101 102 102/101 137 138 138/137 173 174 174/173 30 72 12/5 66 144 24/11 102 216 36/17 138 288 48/23 174 360 60/29 31 32 32/31 67 68 68/67 103 104 104/103 139 140 140/139 175 248 248/175 32 63 63/32 68 126 63/34 104 210 105/52 140 336 12/5 176 372 93/44 33 48 16/11 69 96 32/23 105 192 64/35 141 192 64/47 177 240 80/59 34 54 27/17 70 144 72/35 106 162 81/53 142 216 108/71 178 270 135/89 35 48 48/35 71 72 72/71 107 108 108/107 143 168 168/143 179 180 180/179 36 91 91/36 72 195 65/24 108 280 70/27 144 403 403/144 180 546 91/30