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 | 1 |
| 2 | 4 |
| 3 | 19 |
| 4 | 100 |
| 5 | 562 |
| 6 | 3304 |
| 7 | 20071 |
| 8 | 124996 |
| 9 | 793774 |
| 10 | 5120632 |
| 11 | 33463102 |
| 12 | 221060008 |
| 13 | 1473830308 |
| 14 | 9904186192 |
| 15 | 67015401391 |
| 16 | 456192667396 |
| 17 | 3122028222934 |
| 18 | 21467769499864 |
| 19 | 148246598341018 |
| 20 | 1027656663676600 |
| 21 | 7148588698592956 |
| 22 | 49884553176689584 |