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 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 40 |
| 5 | 205 |
| 6 | 991 |
| 7 | 4612 |
| 8 | 20905 |
| 9 | 92935 |
| 10 | 407056 |
| 11 | 1762117 |
| 12 | 7556095 |
| 13 | 32148940 |
| 14 | 135892321 |
| 15 | 571232647 |
| 16 | 2389810360 |
| 17 | 9956870845 |
| 18 | 41335010911 |
| 19 | 171055514452 |
| 20 | 705891052825 |
| 21 | 2905717608775 |
| 22 | 11934337612576 |
| 23 | 48918212175157 |
| 24 | 200149835407615 |
| 25 | 817572886925980 |