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 | 3 |
| 3 | 10 |
| 4 | 48 |
| 5 | 195 |
| 6 | 840 |
| 7 | 3536 |
| 8 | 15015 |
| 9 | 63546 |
| 10 | 269280 |
| 11 | 1140535 |
| 12 | 4831632 |
| 13 | 20466720 |
| 14 | 86699067 |
| 15 | 367262090 |
| 16 | 1555748880 |
| 17 | 6590255259 |
| 18 | 27916773720 |
| 19 | 118257343984 |
| 20 | 500946159615 |
| 21 | 2122041966330 |
| 22 | 8989114051008 |
| 23 | 38078498128175 |
| 24 | 161303106631968 |
| 25 | 683290924545600 |