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 | -1 |
| 3 | 9 |
| 4 | -47 |
| 5 | 299 |
| 6 | -1953 |
| 7 | 13231 |
| 8 | -91729 |
| 9 | 647433 |
| 10 | -4633499 |
| 11 | 33531761 |
| 12 | -244884159 |
| 13 | 1802040241 |
| 14 | -13346305519 |
| 15 | 99392117841 |
| 16 | -743734839215 |
| 17 | 5588564785067 |
| 18 | -42148760792553 |
| 19 | 318928716891883 |
| 20 | -2420342154102853 |
| 21 | 18416484881248743 |
| 22 | -140466988872011009 |
| 23 | 1073705008744247231 |
| 24 | -8223501739695527745 |