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 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 30 |
| 6 | 103 |
| 7 | 375 |
| 8 | 1400 |
| 9 | 5380 |
| 10 | 21073 |
| 11 | 83950 |
| 12 | 338878 |
| 13 | 1383576 |
| 14 | 5702485 |
| 15 | 23696081 |
| 16 | 99163323 |
| 17 | 417553252 |
| 18 | 1767827220 |
| 19 | 7520966100 |
| 20 | 32135955585 |
| 21 | 137849390424 |
| 22 | 593407692685 |
| 23 | 2562695780058 |
| 24 | 11099806544050 |
| 25 | 48206136562750 |
| 26 | 209876865026303 |
| 27 | 915840095739301 |