+--------+------------+
| length | prime      |
+--------+------------+
|      6 |        139 |
|      7 |        617 |
|      8 |       1069 |
|      9 |       3389 |
|     10 |      11497 |
|     11 |      17863 |
|     12 |      58013 |
|     13 |     136859 |
|     14 |     239873 |
|     15 |     608789 |
|     16 |    1091339 |
|     17 |    2899861 |
|     18 |    5357603 |
|     19 |   13919273 |
|     20 |   27700919 |
|     21 |   70483537 |
|     22 |  122954173 |
|     23 |  282097363 |
|     24 |  477395357 |
|     25 | 1138900957 | -- optimal?
|     26 | 1181362571 |
|     27 | 1188373009 |
|     28 | 1189679171 |
|     29 | 1189679201 |
|     30 | 1189679021 |
|     31 | 1189679069 |
|     32 | 1189678981 |
|     33 | 1189679173 |
|     34 | 1189678879 |
|     35 | 1189679063 |
|     36 | 1189674401 |
|     37 | 1189679041 |
|     38 | 1189675369 |
|     39 | 1183734623 |
|     40 | 1181280767 |
|     41 | 1179693209 |
|     42 | 1180521577 |
|     43 | 1181502713 |
|     44 | 1181495831 |
|     45 | 1177256659 |
|     46 | 1183881169 |
|     47 | 1178034049 |
|     48 | 1173106679 |
|     49 | 1174250113 |
|     50 | 1173958369 |
|     51 | 1143271561 |
|     52 | 1144336033 |
|     53 | 1139894929 |
|     54 | 1177542911 |
|     55 | 1041430153 |
|     56 | 1119841529 |
|     57 | 1079709649 |
|     58 | 1180683001 |
|     59 |  634711921 |
|     60 | 1146975959 |
|     61 | 1054287809 |
|     62 | 1180681441 |
|     64 |  947815391 |
|     66 | 1052665507 |
|     68 | 1115616479 |
|     72 | 1113314879 |
|     74 | 1179613681 |
|     76 |   40754999 |
|     80 |  688333799 |
|     82 | 1177310689 |
|     84 |  131486759 |
|     86 | 1181277241 |
|     94 | 1174448521 |
|    106 | 1163729449 |
|    118 | 1135352761 |
|    122 | 1138435489 |
|    134 | 1154733889 |
|    142 | 1008273289 |
|    158 |  427733329 |
|    166 |  898716289 |
+--------+------------+

Last updated 22 Feb 2021