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 | 4 |
| 2 | 30 |
| 3 | 272 |
| 4 | 2737 |
| 5 | 29380 |
| 6 | 329614 |
| 7 | 3818540 |
| 8 | 45329440 |
| 9 | 548511612 |
| 10 | 6740687924 |
| 11 | 83898110660 |
| 12 | 1055441468145 |
| 13 | 13398494365088 |
| 14 | 171422870731600 |
| 15 | 2208161418665872 |
| 16 | 28614197357895055 |
| 17 | 372754395074051500 |
| 18 | 4878709294080115494 |
| 19 | 64123505084010848580 |
| 20 | 846018700129069313495 |