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 | 38 |
| 4 | 276 |
| 5 | 1270 |
| 6 | 4745 |
| 7 | 15936 |
| 8 | 50608 |
| 9 | 156116 |
| 10 | 474585 |
| 11 | 1432450 |
| 12 | 4309076 |
| 13 | 12942618 |
| 14 | 38847601 |
| 15 | 116567660 |
| 16 | 349733760 |
| 17 | 1049238856 |
| 18 | 3147761873 |
| 19 | 9443339646 |
| 20 | 28330082740 |
| 21 | 84990322910 |
| 22 | 254971055481 |
| 23 | 764913266488 |
| 24 | 2294739914096 |
| 25 | 6884219872860 |
| 26 | 20652659766505 |