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 | 3 |
| 3 | 16 |
| 4 | 84 |
| 5 | 459 |
| 6 | 2552 |
| 7 | 14378 |
| 8 | 81783 |
| 9 | 468622 |
| 10 | 2700926 |
| 11 | 15640800 |
| 12 | 90930523 |
| 13 | 530391615 |
| 14 | 3102491160 |
| 15 | 18192186330 |
| 16 | 106901798100 |
| 17 | 629361849402 |
| 18 | 3711413384462 |
| 19 | 21919199253088 |
| 20 | 129625701167820 |