420 Numbers with many repeating digits
Appendix: Factorization of 10 n+1for 1 ≤n≤ 50
n Factorization of 10n+1
111
2101
37 × 11 × 13
473 × 137
511 × 9091
6101 × 9901
711 × 909091
817 × 5882353
97 × 11 × 13 × 19 × 52579
10 101× 3541 × 27961
11 11^2 × 23 × 4093 × 8779
12 73× 137 × 99990001
13 11× 859 × 1058313049
14 29× 101 × 281 × 121499449
15 7× 11 × 13 × 211 × 241 × 2161 × 9091
16 353× 449 × 641 × 1409 × 69857
17 11× 103 × 4013 × 21993833369
18 101× 9901 × 999999000001
19 11× 909090909090909091
20 73× 137 × 1676321 × 5964848081
21 7^2 × 11 × 13 × 127 × 2689 × 459691 × 909091
22 89× 101 × 1052788969 × 1056689261
23 11× 47 × 139 × 2531 × 549797184491917
24 17× 5882353 × 9999999900000001
25 11× 251 × 5051 × 9091 × 78875943472201
26 101× 521 × 1900381976777332243781
27 7× 11 × 13 × 19 × 52579 × 70541929 × 14175966169
28 73× 137 × 7841 × 127522001020150503761
29 11× 59 × 154083204930662557781201849
30 61× 101 × 3541 × 9901 × 27961 × 4188901 × 39526741
31 11× 909090909090909090909090909091
32 19841× 976193 × 6187457 × 834427406578561
33 7× 112 × 13 × 23 × 4093 × 8779 × 599144041 × 183411838171
34 101× 28559389 × 1491383821 × 2324557465671829
35 11× 9091 × 909091 × 4147571 × 265212793249617641
36 73× 137 × 3169 × 98641 × 99990001 × 3199044596370769
37 11× 7253 × 422650073734453 × 296557347313446299
38 101× 722817036322379041 × 1369778187490592461
39 7× 11 × 132 × 157 × 859 × 6397 × 216451 × 1058313049 × 388847808493
40 17× 5070721 × 5882353 × 19721061166646717498359681
41 11× 2670502781396266997 × 3404193829806058997303
42 29× 101 × 281 × 9901 × 226549 × 121499449 × 4458192223320340849
43 11× 57009401 × 2182600451 × 7306116556571817748755241
44 73× 137 × 617 × 16205834846012967584927082656402106953
45 7× 11 × 13 × 19 × 211 × 241 × 2161 × 9091 × 29611 × 52579
× 3762091 × 8985695684401
46 101× 1289 × 18371524594609 × 4181003300071669867932658901
47 11× 6299 × 4855067598095567 × 297262705009139006771611927
48 97× 353 × 449 × 641 × 1409 × 69857 × 206209 × 66554101249 × 75118313082913
49 11× 197 × 909091 × 5076141624365532994918781726395939035533
50 101× 3541 × 27961 × 60101 × 7019801 × 14103673319201 × 1680588011350901