This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 1 |
| 3 | 12 |
| 4 | 1 |
| 5 | 60 |
| 6 | 1 |
| 7 | 252 |
| 8 | 1 |
| 9 | 1020 |
| 10 | 1 |
| 11 | 4092 |
| 12 | 1 |
| 13 | 16380 |
| 14 | 1 |
| 15 | 65532 |
| 16 | 1 |
| 17 | 262140 |
| 18 | 1 |
| 19 | 1048572 |
| 20 | 1 |
| 21 | 4194300 |
| 22 | 1 |
| 23 | 16777212 |
| 24 | 1 |
| 25 | 67108860 |
| 26 | 1 |
| 27 | 268435452 |
| 28 | 1 |
| 29 | 1073741820 |
| 30 | 1 |
| 31 | 4294967292 |
| 32 | 1 |
| 33 | 17179869180 |
| 34 | 1 |
| 35 | 68719476732 |
| 36 | 1 |
| 37 | 274877906940 |
| 38 | 1 |
| 39 | 1099511627772 |
| 40 | 1 |
| 41 | 4398046511100 |
| 42 | 1 |