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 | 5 |
| 3 | 33 |
| 4 | 285 |
| 5 | 3081 |
| 6 | 40005 |
| 7 | 606033 |
| 8 | 10491885 |
| 9 | 204343641 |
| 10 | 4422082005 |
| 11 | 105265315233 |
| 12 | 2733583519485 |
| 13 | 76902684021801 |
| 14 | 2329889536156005 |
| 15 | 75629701786875633 |
| 16 | 2618654297178083085 |
| 17 | 96336948993312237561 |
| 18 | 3752590641305604502005 |
| 19 | 154294551397830418471233 |
| 20 | 6677999524135208461382685 |