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 | 3 |
| 3 | 13 |
| 4 | 75 |
| 5 | 541 |
| 6 | 4683 |
| 7 | 47293 |
| 8 | 545834 |
| 9 | 7087242 |
| 10 | 102247182 |
| 11 | 1622624850 |
| 12 | 28091404902 |
| 13 | 526854753282 |
| 14 | 10641259374174 |
| 15 | 230281144233426 |
| 16 | 5315601950221992 |
| 17 | 130369339178641992 |
| 18 | 3385494089758915992 |
| 19 | 92800379366660198376 |
| 20 | 2677650178353887869704 |