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 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 0 |
| 4 | 16 |
| 5 | 5 |
| 6 | 288 |
| 7 | 392 |
| 8 | 9840 |
| 9 | 33462 |
| 10 | 582910 |
| 11 | 3652044 |
| 12 | 55557192 |
| 13 | 524095728 |
| 14 | 7910319116 |
| 15 | 98390834310 |
| 16 | 1573086910848 |
| 17 | 23774700449584 |
| 18 | 414180226506456 |
| 19 | 7249907657342184 |
| 20 | 138771378745878680 |
| 21 | 2735366111451910944 |
| 22 | 57469663931297252976 |
| 23 | 1253755421949789141624 |