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 | 5 |
| 4 | 21 |
| 5 | 105 |
| 6 | 636 |
| 7 | 4507 |
| 8 | 36449 |
| 9 | 330947 |
| 10 | 3334302 |
| 11 | 36913401 |
| 12 | 445422501 |
| 13 | 5818511965 |
| 14 | 81805201736 |
| 15 | 1231687676375 |
| 16 | 19772907413361 |
| 17 | 337146208373847 |
| 18 | 6085000404767514 |
| 19 | 115897246212304837 |
| 20 | 2323089762369102677 |
| 21 | 48883749655553977121 |
| 22 | 1077440067884422805556 |