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) |
|---|---|
| 4 | 1 |
| 5 | 15 |
| 6 | 141 |
| 7 | 1070 |
| 8 | 7187 |
| 9 | 44673 |
| 10 | 263431 |
| 11 | 1496218 |
| 12 | 8266100 |
| 13 | 44718596 |
| 14 | 238015318 |
| 15 | 1250656153 |
| 16 | 6504202391 |
| 17 | 33543967700 |
| 18 | 171810543570 |
| 19 | 875006817465 |
| 20 | 4435130657170 |
| 21 | 22390449598704 |
| 22 | 112654298838120 |
| 23 | 565172299571352 |