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 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 20 |
| 5 | 110 |
| 6 | 638 |
| 7 | 3828 |
| 8 | 23515 |
| 9 | 146968 |
| 10 | 930797 |
| 11 | 5957100 |
| 12 | 38450370 |
| 13 | 249927394 |
| 14 | 1634140604 |
| 15 | 10738638021 |
| 16 | 70875009760 |
| 17 | 469546933535 |
| 18 | 3121106054760 |
| 19 | 20807373517870 |
| 20 | 139080864081230 |
| 21 | 931841783576460 |
| 22 | 6256651942091035 |
| 23 | 42090203778813320 |
| 24 | 283651372136401905 |
| 25 | 1914646755015446620 |