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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 10 |
| 5 | -68 |
| 6 | 1468 |
| 7 | -7929 |
| 8 | 35072 |
| 9 | -119725 |
| 10 | 493832 |
| 11 | -2710587 |
| 12 | 16059277 |
| 13 | -98261260 |
| 14 | 525451031 |
| 15 | -2507345569 |
| 16 | 10710363936 |
| 17 | -53022448430 |
| 18 | 267677021793 |
| 19 | -1382764429433 |
| 20 | 7106604185917 |
| 21 | -37800524142826 |
| 22 | 196740300088086 |
| 23 | -956326625126632 |