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 | 2 |
| 2 | -4 |
| 3 | 15 |
| 4 | -44 |
| 5 | 385 |
| 6 | -294 |
| 7 | 32473 |
| 8 | 280120 |
| 9 | 8528049 |
| 10 | 170757910 |
| 11 | 4748977321 |
| 12 | 132530188308 |
| 13 | 4210910824393 |
| 14 | 142940443542274 |
| 15 | 5273270156096265 |
| 16 | 208276214340505456 |
| 17 | 8800344095155520353 |
| 18 | 395536292522024420142 |
| 19 | 18853858817276143333321 |
| 20 | 949787282108877829653580 |