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 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 12 |
| 4 | 93 |
| 5 | 840 |
| 6 | 9183 |
| 7 | 117012 |
| 8 | 1704153 |
| 9 | 27921360 |
| 10 | 508302363 |
| 11 | 10178888412 |
| 12 | 222365364213 |
| 13 | 5262547606680 |
| 14 | 134124963385143 |
| 15 | 3662574088282212 |
| 16 | 106682195378484273 |
| 17 | 3301614846549616800 |
| 18 | 108189336403552025523 |
| 19 | 3742170760095124874412 |