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 | 6 |
| 3 | 19 |
| 4 | 62 |
| 5 | 207 |
| 6 | 704 |
| 7 | 2430 |
| 8 | 8486 |
| 9 | 29903 |
| 10 | 106098 |
| 11 | 378391 |
| 12 | 1354700 |
| 13 | 4863834 |
| 14 | 17499302 |
| 15 | 63055947 |
| 16 | 227465414 |
| 17 | 821215295 |
| 18 | 2966571096 |
| 19 | 10721076118 |
| 20 | 38757594758 |
| 21 | 140143505031 |
| 22 | 506827217210 |
| 23 | 1833150646599 |
| 24 | 6630915738212 |
| 25 | 23986989146162 |
| 26 | 86775559512774 |
| 27 | 313930265564035 |