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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 31 |
| 5 | 93 |
| 6 | 119 |
| 7 | 2709 |
| 8 | 38937 |
| 9 | 520831 |
| 10 | 682341 |
| 11 | 340134981 |
| 12 | 7609865031 |
| 13 | 17935304097 |
| 14 | 26777829859 |
| 15 | 169179279801 |
| 16 | 567897922593 |
| 17 | 286118927218753 |
| 18 | 2996750083037781 |
| 19 | 4738749440161121 |
| 20 | 6299497017331917 |
| 21 | 8829547069230943 |