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 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 1 |
| 5 | 1 |
| 6 | 3 |
| 7 | 6 |
| 8 | 14 |
| 9 | 42 |
| 10 | 121 |
| 11 | 384 |
| 12 | 1408 |
| 13 | 5100 |
| 14 | 21854 |
| 15 | 92234 |
| 16 | 427079 |
| 17 | 2005800 |
| 18 | 9716848 |
| 19 | 48184018 |
| 20 | 241210386 |
| 21 | 1228973463 |
| 22 | 6301831944 |
| 23 | 32663182521 |
| 24 | 170407462900 |