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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 28 |
| 5 | 170 |
| 6 | 866 |
| 7 | 4025 |
| 8 | 17704 |
| 9 | 75108 |
| 10 | 310812 |
| 11 | 1263823 |
| 12 | 5075104 |
| 13 | 20198854 |
| 14 | 79878696 |
| 15 | 314426897 |
| 16 | 1233391952 |
| 17 | 4824992904 |
| 18 | 18832070706 |
| 19 | 73352680695 |
| 20 | 285181117292 |
| 21 | 1106813965234 |
| 22 | 4288993897696 |
| 23 | 16598629303781 |
| 24 | 64176110700560 |
| 25 | 247997873779100 |
| 26 | 958343137325810 |