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 | 12 |
| 2 | 72 |
| 3 | 360 |
| 4 | 2080 |
| 5 | 12232 |
| 6 | 73656 |
| 7 | 449440 |
| 8 | 2770016 |
| 9 | 17195112 |
| 10 | 107304872 |
| 11 | 672224048 |
| 12 | 4223186080 |
| 13 | 26586825472 |
| 14 | 167628931360 |
| 15 | 1058056409920 |
| 16 | 6683674433920 |
| 17 | 42244783230496 |
| 18 | 267124015799712 |
| 19 | 1689602502335776 |