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 | 29 |
| 5 | 225 |
| 6 | 1669 |
| 7 | 14245 |
| 8 | 118705 |
| 9 | 1118001 |
| 10 | 11705019 |
| 11 | 144091717 |
| 12 | 1738439017 |
| 13 | 24817157329 |
| 14 | 355309322689 |
| 15 | 5378578597729 |
| 16 | 86081749391905 |
| 17 | 1570394279028289 |
| 18 | 28281459220178401 |
| 19 | 572031558109560385 |
| 20 | 11458497230555053681 |