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 | 3 |
| 2 | 9 |
| 3 | 30 |
| 4 | 99 |
| 5 | 327 |
| 6 | 1080 |
| 7 | 3567 |
| 8 | 11781 |
| 9 | 38910 |
| 10 | 128511 |
| 11 | 424443 |
| 12 | 1401840 |
| 13 | 4629963 |
| 14 | 15291729 |
| 15 | 50505150 |
| 16 | 166807179 |
| 17 | 550926687 |
| 18 | 1819587240 |
| 19 | 6009688407 |
| 20 | 19848652461 |
| 21 | 65555645790 |
| 22 | 216515589831 |
| 23 | 715102415283 |
| 24 | 2361822835680 |