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 | -1 |
| 3 | 1 |
| 4 | -4 |
| 5 | 17 |
| 6 | -86 |
| 7 | 514 |
| 8 | -3599 |
| 9 | 28809 |
| 10 | -259285 |
| 11 | 2592766 |
| 12 | -28520427 |
| 13 | 342245654 |
| 14 | -4449193503 |
| 15 | 62288705445 |
| 16 | -934330581764 |
| 17 | 14949289337033 |
| 18 | -254137918729562 |
| 19 | 4574482536873349 |
| 20 | -86915168200593632 |
| 21 | 1738303364014465422 |
| 22 | -36504370644303777464 |
| 23 | 803096154174654583783 |
| 24 | -18471211546017055427010 |