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 | 2 |
| 3 | 3 |
| 4 | 7 |
| 5 | 15 |
| 6 | 56 |
| 7 | 176 |
| 8 | 1002 |
| 9 | 5604 |
| 10 | 53174 |
| 11 | 526823 |
| 12 | 10619863 |
| 13 | 214481126 |
| 14 | 9035836076 |
| 15 | 476715857290 |
| 16 | 51820051838712 |
| 17 | 7479565078510584 |
| 18 | 2645418340688763701 |
| 19 | 1318520401612270233223 |
| 20 | 1774758704783877366657989 |
| 21 | 4025091510519029370421431033 |