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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 20 |
| 6 | 51 |
| 7 | 154 |
| 8 | 460 |
| 9 | 1476 |
| 10 | 4860 |
| 11 | 16544 |
| 12 | 57321 |
| 13 | 202059 |
| 14 | 720370 |
| 15 | 2593470 |
| 16 | 9408000 |
| 17 | 34350506 |
| 18 | 126108252 |
| 19 | 465200332 |
| 20 | 1723341185 |
| 21 | 6408356052 |
| 22 | 23911255544 |
| 23 | 89495909408 |
| 24 | 335916703284 |
| 25 | 1264114452975 |
| 26 | 4768464107355 |