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 | 4 |
| 4 | 16 |
| 5 | 56 |
| 6 | 190 |
| 7 | 624 |
| 8 | 2014 |
| 9 | 6412 |
| 10 | 20219 |
| 11 | 63284 |
| 12 | 196938 |
| 13 | 610052 |
| 14 | 1882717 |
| 15 | 5792528 |
| 16 | 17776102 |
| 17 | 54433100 |
| 18 | 166374109 |
| 19 | 507710420 |
| 20 | 1547195902 |
| 21 | 4709218604 |
| 22 | 14318240578 |
| 23 | 43493134160 |
| 24 | 132003957436 |
| 25 | 400337992056 |
| 26 | 1213314272395 |
| 27 | 3674980475284 |
| 28 | 11124919273160 |