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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 6 |
| 6 | 15 |
| 7 | 36 |
| 8 | 114 |
| 9 | 396 |
| 10 | 1565 |
| 11 | 6756 |
| 12 | 31563 |
| 13 | 154370 |
| 14 | 785113 |
| 15 | 4099948 |
| 16 | 21870704 |
| 17 | 118624544 |
| 18 | 652485364 |
| 19 | 3631820462 |
| 20 | 20426666644 |
| 21 | 115949791342 |
| 22 | 663640383400 |
| 23 | 3826858500878 |
| 24 | 22218232389849 |
| 25 | 129802836253994 |