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 | 4 |
| 2 | 28 |
| 3 | 232 |
| 4 | 2056 |
| 5 | 18784 |
| 6 | 174112 |
| 7 | 1625152 |
| 8 | 15220288 |
| 9 | 142777600 |
| 10 | 1340416768 |
| 11 | 12588825088 |
| 12 | 118252556800 |
| 13 | 1110898849792 |
| 14 | 10436554713088 |
| 15 | 98050271875072 |
| 16 | 921180638875648 |
| 17 | 8654518327066624 |
| 18 | 81309636020912128 |