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 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 35 |
| 5 | 256 |
| 6 | 2187 |
| 7 | 21620 |
| 8 | 243947 |
| 9 | 3098528 |
| 10 | 43799819 |
| 11 | 682540780 |
| 12 | 11630529643 |
| 13 | 215190967544 |
| 14 | 4296657514283 |
| 15 | 92083313483300 |
| 16 | 2108244638675035 |
| 17 | 51350077108834832 |
| 18 | 1325682930813985547 |
| 19 | 36157047428501464220 |
| 20 | 1038793351537388253211 |
| 21 | 31354977545074731373512 |