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 | 1 |
| 2 | 3 |
| 3 | 5 |
| 4 | 11 |
| 5 | 23 |
| 6 | 54 |
| 7 | 136 |
| 8 | 374 |
| 9 | 1103 |
| 10 | 3441 |
| 11 | 11186 |
| 12 | 37472 |
| 13 | 128325 |
| 14 | 446834 |
| 15 | 1576251 |
| 16 | 5618950 |
| 17 | 20204874 |
| 18 | 73190075 |
| 19 | 266810125 |
| 20 | 978044403 |
| 21 | 3602795670 |
| 22 | 13329486459 |
| 23 | 49509151332 |
| 24 | 184540129492 |
| 25 | 690061739789 |
| 26 | 2587941606367 |
| 27 | 9731587992993 |