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 | 4 |
| 3 | 16 |
| 4 | 66 |
| 5 | 281 |
| 6 | 1232 |
| 7 | 5548 |
| 8 | 25598 |
| 9 | 120724 |
| 10 | 580658 |
| 11 | 2842222 |
| 12 | 14129842 |
| 13 | 71212849 |
| 14 | 363242996 |
| 15 | 1872444764 |
| 16 | 9741516322 |
| 17 | 51092414488 |
| 18 | 269881127838 |
| 19 | 1434527328782 |
| 20 | 7667466737670 |
| 21 | 41184478999300 |
| 22 | 222189902624502 |
| 23 | 1203447917249894 |