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 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 31 |
| 6 | 76 |
| 7 | 218 |
| 8 | 645 |
| 9 | 1849 |
| 10 | 5281 |
| 11 | 15346 |
| 12 | 44980 |
| 13 | 131704 |
| 14 | 385568 |
| 15 | 1131874 |
| 16 | 3331429 |
| 17 | 9819405 |
| 18 | 28977079 |
| 19 | 85633438 |
| 20 | 253424053 |
| 21 | 750895163 |
| 22 | 2227288196 |
| 23 | 6613217348 |
| 24 | 19654450476 |
| 25 | 58463536356 |
| 26 | 174041552556 |
| 27 | 518488451716 |
| 28 | 1545686334184 |
| 29 | 4610827520500 |