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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 30 |
| 5 | 154 |
| 6 | 924 |
| 7 | 6471 |
| 8 | 51771 |
| 9 | 465947 |
| 10 | 4659471 |
| 11 | 51254185 |
| 12 | 615050229 |
| 13 | 7995652977 |
| 14 | 111939141684 |
| 15 | 1679087125263 |
| 16 | 26865394004209 |
| 17 | 456711698071557 |
| 18 | 8220810565288034 |
| 19 | 156195400740472660 |
| 20 | 3123908014809453215 |