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 | 0 |
| 2 | 2 |
| 3 | 4 |
| 4 | 13 |
| 5 | 145 |
| 6 | 416 |
| 7 | 621 |
| 8 | 1856 |
| 9 | 4730 |
| 10 | 5163 |
| 11 | 8113 |
| 12 | 18260 |
| 13 | 142396 |
| 14 | 1650399 |
| 15 | 6569927 |
| 16 | 19975865 |
| 17 | 23773865 |
| 18 | 371728346 |
| 19 | 517406582 |
| 20 | 642281555 |
| 21 | 864490611 |
| 22 | 1352215149 |
| 23 | 1503350552 |