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 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 22 |
| 6 | 55 |
| 7 | 141 |
| 8 | 371 |
| 9 | 997 |
| 10 | 2712 |
| 11 | 7440 |
| 12 | 20542 |
| 13 | 57056 |
| 14 | 159343 |
| 15 | 447045 |
| 16 | 1259443 |
| 17 | 3561529 |
| 18 | 10119910 |
| 19 | 28892841 |
| 20 | 82727805 |
| 21 | 237322575 |
| 22 | 681862156 |
| 23 | 1961930899 |
| 24 | 5653182325 |
| 25 | 16312268162 |
| 26 | 47133250093 |
| 27 | 136366337701 |