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 | 0 |
| 3 | 6 |
| 4 | 18 |
| 5 | 78 |
| 6 | 426 |
| 7 | 2790 |
| 8 | 21234 |
| 9 | 183822 |
| 10 | 1781802 |
| 11 | 19104774 |
| 12 | 224406930 |
| 13 | 2864826126 |
| 14 | 39486808938 |
| 15 | 584328412518 |
| 16 | 9238767895026 |
| 17 | 155416555683150 |
| 18 | 2771424197143914 |
| 19 | 52216883883837702 |
| 20 | 1036463580947218962 |
| 21 | 21616958644969620174 |
| 22 | 472612476001411964970 |
| 23 | 10808196686285486012646 |