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 | 4 |
| 3 | 19 |
| 4 | 88 |
| 5 | 401 |
| 6 | 1804 |
| 7 | 8051 |
| 8 | 35760 |
| 9 | 158401 |
| 10 | 700564 |
| 11 | 3095731 |
| 12 | 13673224 |
| 13 | 60375953 |
| 14 | 266559388 |
| 15 | 1176763859 |
| 16 | 5194762080 |
| 17 | 22931453953 |
| 18 | 101225940772 |
| 19 | 446836798675 |
| 20 | 1972442421688 |
| 21 | 8706804701201 |
| 22 | 38433749994028 |