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 | 5 |
| 3 | 21 |
| 4 | 131 |
| 5 | 940 |
| 6 | 7902 |
| 7 | 69025 |
| 8 | 594203 |
| 9 | 4856288 |
| 10 | 37189863 |
| 11 | 265916174 |
| 12 | 1778005595 |
| 13 | 11154474602 |
| 14 | 65921168577 |
| 15 | 368463685296 |
| 16 | 1955231394323 |
| 17 | 9884229508860 |
| 18 | 47752849848446 |
| 19 | 221109815065563 |
| 20 | 983764137502726 |