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 | 6 |
| 4 | 21 |
| 5 | 90 |
| 6 | 450 |
| 7 | 2619 |
| 8 | 17334 |
| 9 | 129114 |
| 10 | 1067661 |
| 11 | 9713682 |
| 12 | 96393726 |
| 13 | 1036348587 |
| 14 | 11998603710 |
| 15 | 148842430470 |
| 16 | 1969461102357 |
| 17 | 27688474234602 |
| 18 | 412166988789642 |
| 19 | 6476330295597051 |
| 20 | 107117619952992966 |
| 21 | 1860296912926495938 |
| 22 | 33845967939906741213 |
| 23 | 643778989807702357314 |