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 | 15 |
| 4 | 105 |
| 5 | 315 |
| 6 | 1141 |
| 7 | 4779 |
| 8 | 21101 |
| 9 | 80559 |
| 10 | 314185 |
| 11 | 1267551 |
| 12 | 5160933 |
| 13 | 20504123 |
| 14 | 81554685 |
| 15 | 326682775 |
| 16 | 1310978305 |
| 17 | 5239019143 |
| 18 | 20931551661 |
| 19 | 83743554723 |
| 20 | 335175239813 |
| 21 | 1340542340399 |
| 22 | 5360923216953 |
| 23 | 21444223178271 |
| 24 | 85786427569333 |
| 25 | 343141430067947 |