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 | 1 |
| 3 | 12 |
| 4 | 193 |
| 5 | 3980 |
| 6 | 100805 |
| 7 | 3034920 |
| 8 | 105994833 |
| 9 | 4215106728 |
| 10 | 188097696345 |
| 11 | 9309515255700 |
| 12 | 506149663220641 |
| 13 | 29989851619249236 |
| 14 | 1923467938147053389 |
| 15 | 132771455705186298000 |
| 16 | 9814431285244231295265 |
| 17 | 773520674985391641371280 |
| 18 | 64752473306596841023424945 |