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 | 1 |
| 4 | 5 |
| 5 | 29 |
| 6 | 239 |
| 7 | 3119 |
| 8 | 65519 |
| 9 | 2227679 |
| 10 | 122522399 |
| 11 | 10904493599 |
| 12 | 1570247078399 |
| 13 | 365867569267199 |
| 14 | 137932073613734399 |
| 15 | 84138564904377983999 |
| 16 | 83044763560621070207999 |
| 17 | 132622487406311849122175999 |
| 18 | 342696507457909818131702783999 |
| 19 | 1432814097681520949608649339903999 |