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 | 0 |
| 2 | 3 |
| 3 | 4 |
| 4 | 25 |
| 5 | 66 |
| 6 | 287 |
| 7 | 960 |
| 8 | 3789 |
| 9 | 13810 |
| 10 | 53240 |
| 11 | 200652 |
| 12 | 771641 |
| 13 | 2952054 |
| 14 | 11386065 |
| 15 | 43910288 |
| 16 | 170007429 |
| 17 | 658979586 |
| 18 | 2560258550 |
| 19 | 9960335060 |
| 20 | 38811668868 |
| 21 | 151418146704 |
| 22 | 591464244882 |
| 23 | 2312774560296 |
| 24 | 9052560751725 |
| 25 | 35464735083726 |
| 26 | 139054217427702 |
| 27 | 545635715465596 |