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) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 21 |
| 5 | 131 |
| 6 | 950 |
| 7 | 7694 |
| 8 | 70343 |
| 9 | 709015 |
| 10 | 7867174 |
| 11 | 94945874 |
| 12 | 1241471451 |
| 13 | 17442660795 |
| 14 | 262748183438 |
| 15 | 4215551220698 |
| 16 | 71873188059263 |
| 17 | 1296535610096063 |
| 18 | 24690833276595022 |
| 19 | 494624740502491786 |
| 20 | 10406110949475668267 |
| 21 | 229244825016301188267 |
| 22 | 5280217980442316367510 |