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 | 1 |
| 2 | 5 |
| 3 | 31 |
| 4 | 151 |
| 5 | 917 |
| 6 | 5619 |
| 7 | 33627 |
| 8 | 210911 |
| 9 | 1326395 |
| 10 | 8366161 |
| 11 | 53441835 |
| 12 | 342477957 |
| 13 | 2203613164 |
| 14 | 14248253995 |
| 15 | 92379163952 |
| 16 | 600644552471 |
| 17 | 3915699367751 |
| 18 | 25579440322831 |
| 19 | 167423682425912 |
| 20 | 1097738520430457 |
| 21 | 7208383257398805 |