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 | 12 |
| 3 | 108 |
| 4 | 1156 |
| 5 | 12435 |
| 6 | 137292 |
| 7 | 1528688 |
| 8 | 17232084 |
| 9 | 195170310 |
| 10 | 2228154512 |
| 11 | 25506741084 |
| 12 | 293661065788 |
| 13 | 3386455204288 |
| 14 | 39222848622984 |
| 15 | 454745042732160 |
| 16 | 5290621952635476 |
| 17 | 61590267941514516 |
| 18 | 719050614048219912 |
| 19 | 8397773337294253140 |
| 20 | 98314091309732350656 |