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 | 4 |
| 3 | 38 |
| 4 | 444 |
| 5 | 5805 |
| 6 | 81284 |
| 7 | 1192144 |
| 8 | 18078660 |
| 9 | 281172017 |
| 10 | 4460264072 |
| 11 | 71886775636 |
| 12 | 1173832034804 |
| 13 | 19377733213699 |
| 14 | 322866234066016 |
| 15 | 5422493523853024 |
| 16 | 91701823351874276 |
| 17 | 1560232214582865621 |
| 18 | 26688686144512908492 |