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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 22 |
| 6 | 77 |
| 7 | 210 |
| 8 | 673 |
| 9 | 1934 |
| 10 | 5973 |
| 11 | 17578 |
| 12 | 53417 |
| 13 | 158886 |
| 14 | 479389 |
| 15 | 1432706 |
| 16 | 4309041 |
| 17 | 12905278 |
| 18 | 38759525 |
| 19 | 116191194 |
| 20 | 348748345 |
| 21 | 1045895510 |
| 22 | 3138385581 |
| 23 | 9413758642 |
| 24 | 28244072129 |
| 25 | 84726623982 |
| 26 | 254191056757 |
| 27 | 762550800650 |
| 28 | 2287697141193 |
| 29 | 6863001945094 |