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 | 2 |
| 2 | 4 |
| 3 | 10 |
| 4 | 36 |
| 5 | 132 |
| 6 | 532 |
| 7 | 2222 |
| 8 | 9584 |
| 9 | 42248 |
| 10 | 189776 |
| 11 | 864830 |
| 12 | 3989656 |
| 13 | 18593424 |
| 14 | 87413444 |
| 15 | 414060796 |
| 16 | 1974260912 |
| 17 | 9467922870 |
| 18 | 45638482068 |
| 19 | 221001289714 |
| 20 | 1074591477112 |
| 21 | 5244497440468 |
| 22 | 25681907242416 |
| 23 | 126149132242490 |
| 24 | 621386729646752 |
| 25 | 3068748094479108 |