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 | 1 |
| 2 | 5 |
| 3 | 24 |
| 4 | 114 |
| 5 | 540 |
| 6 | 2556 |
| 7 | 12096 |
| 8 | 57240 |
| 9 | 270864 |
| 10 | 1281744 |
| 11 | 6065280 |
| 12 | 28701216 |
| 13 | 135815616 |
| 14 | 642686400 |
| 15 | 3041224704 |
| 16 | 14391229824 |
| 17 | 68100030720 |
| 18 | 322252805376 |
| 19 | 1524916647936 |
| 20 | 7215983055360 |
| 21 | 34146398444544 |
| 22 | 161582492335104 |
| 23 | 764616563343360 |
| 24 | 3618204426049536 |