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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 63 |
| 6 | 215 |
| 7 | 749 |
| 8 | 2650 |
| 9 | 9490 |
| 10 | 34318 |
| 11 | 125104 |
| 12 | 459152 |
| 13 | 1694914 |
| 14 | 6287896 |
| 15 | 23429158 |
| 16 | 87635243 |
| 17 | 328917615 |
| 18 | 1238303243 |
| 19 | 4674847097 |
| 20 | 17692789741 |
| 21 | 67114622451 |
| 22 | 255120892105 |
| 23 | 971649360211 |
| 24 | 3707176155659 |
| 25 | 14167390221873 |