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 | 3 |
| 2 | 31 |
| 3 | 135 |
| 4 | 1015 |
| 5 | 5271 |
| 6 | 34903 |
| 7 | 196311 |
| 8 | 1230295 |
| 9 | 7172055 |
| 10 | 43871191 |
| 11 | 259871703 |
| 12 | 1572651991 |
| 13 | 9382224855 |
| 14 | 56508097495 |
| 15 | 338189591511 |
| 16 | 2032573522903 |
| 17 | 12181697242071 |
| 18 | 73145159033815 |
| 19 | 438651051877335 |
| 20 | 2632785920566231 |
| 21 | 15793197086188503 |
| 22 | 94773256265966551 |