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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 12 |
| 6 | 33 |
| 7 | 90 |
| 8 | 261 |
| 9 | 765 |
| 10 | 2309 |
| 11 | 7058 |
| 12 | 21932 |
| 13 | 68843 |
| 14 | 218378 |
| 15 | 698268 |
| 16 | 2249370 |
| 17 | 7291072 |
| 18 | 23766308 |
| 19 | 77850244 |
| 20 | 256141505 |
| 21 | 846090860 |
| 22 | 2804864997 |
| 23 | 9328658392 |
| 24 | 31118365152 |
| 25 | 104086821258 |
| 26 | 349029100890 |
| 27 | 1173087112579 |
| 28 | 3951183698640 |
| 29 | 13334782347941 |