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 | 6 |
| 2 | 26 |
| 3 | 96 |
| 4 | 316 |
| 5 | 936 |
| 6 | 2456 |
| 7 | 5376 |
| 8 | 7696 |
| 9 | -7584 |
| 10 | -122464 |
| 11 | -658944 |
| 12 | -2729024 |
| 13 | -9784704 |
| 14 | -31417984 |
| 15 | -90660864 |
| 16 | -229785344 |
| 17 | -472103424 |
| 18 | -534767104 |
| 19 | 1512431616 |
| 20 | 14422260736 |
| 21 | 71409248256 |
| 22 | 284232882176 |
| 23 | 991304810496 |
| 24 | 3105500041216 |
| 25 | 8719952142336 |
| 26 | 21264712441856 |
| 27 | 40388753227776 |