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 | 2 |
| 2 | 13 |
| 3 | 71 |
| 4 | 424 |
| 5 | 2579 |
| 6 | 15985 |
| 7 | 100295 |
| 8 | 635176 |
| 9 | 4051649 |
| 10 | 25993366 |
| 11 | 167543354 |
| 12 | 1084134346 |
| 13 | 7038291098 |
| 14 | 45821937982 |
| 15 | 299045487602 |
| 16 | 1955803426045 |
| 17 | 12815265660680 |
| 18 | 84111082917925 |
| 19 | 552872886403775 |
| 20 | 3638971619401720 |