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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 3420 |
| 7 | 576856 |
| 8 | 19760512 |
| 9 | 270487188 |
| 10 | 2209065700 |
| 11 | 12914201256 |
| 12 | 59659859232 |
| 13 | 231216019632 |
| 14 | 781647658596 |
| 15 | 2367858314700 |
| 16 | 6553746728448 |
| 17 | 16815788711212 |
| 18 | 40446802230372 |
| 19 | 92003239814224 |
| 20 | 199311860224800 |
| 21 | 413589922308360 |
| 22 | 825997764087012 |
| 23 | 1594007700404532 |
| 24 | 2982430581363072 |
| 25 | 5425904270482500 |
| 26 | 9622254525739492 |
| 27 | 16669554533555832 |
| 28 | 28264133502586912 |
| 29 | 46982453295836640 |
| 30 | 76676963241363300 |