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 | 1 |
| 2 | 10 |
| 3 | 121 |
| 4 | 1440 |
| 5 | 17161 |
| 6 | 204490 |
| 7 | 2436721 |
| 8 | 29036160 |
| 9 | 345997201 |
| 10 | 4122930250 |
| 11 | 49129165801 |
| 12 | 585427059360 |
| 13 | 6975995546521 |
| 14 | 83126519498890 |
| 15 | 990542238440161 |
| 16 | 11803380341783040 |
| 17 | 140650021862956321 |
| 18 | 1675996882013692810 |
| 19 | 19971312562301357401 |
| 20 | 237979753865602596000 |