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 | 2 |
| 3 | 10 |
| 4 | 39 |
| 5 | 150 |
| 6 | 545 |
| 7 | 2010 |
| 8 | 7320 |
| 9 | 26880 |
| 10 | 98775 |
| 11 | 365010 |
| 12 | 1353185 |
| 13 | 5038950 |
| 14 | 18830145 |
| 15 | 70623958 |
| 16 | 265737270 |
| 17 | 1002976350 |
| 18 | 3796197160 |
| 19 | 14406059010 |
| 20 | 54801140307 |
| 21 | 208932573650 |
| 22 | 798218035245 |
| 23 | 3055417070010 |
| 24 | 11716354754030 |
| 25 | 45002103387120 |
| 26 | 173117601112575 |