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 | 4 |
| 2 | 28 |
| 3 | 232 |
| 4 | 2092 |
| 5 | 19864 |
| 6 | 195352 |
| 7 | 1970896 |
| 8 | 20275660 |
| 9 | 211823836 |
| 10 | 2240798048 |
| 11 | 23951367224 |
| 12 | 258257552968 |
| 13 | 2805581350056 |
| 14 | 30676425237024 |
| 15 | 337324008602512 |
| 16 | 3727882769574860 |
| 17 | 41381900166952348 |
| 18 | 461201577710442388 |
| 19 | 5158610797198820800 |