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 | -3 |
| 3 | 14 |
| 4 | -78 |
| 5 | 479 |
| 6 | -3131 |
| 7 | 21372 |
| 8 | -150588 |
| 9 | 1087057 |
| 10 | -7998295 |
| 11 | 59763129 |
| 12 | -452257495 |
| 13 | 3459109408 |
| 14 | -26697940390 |
| 15 | 207672518808 |
| 16 | -1626400971710 |
| 17 | 12813379464399 |
| 18 | -101482102525511 |
| 19 | 807524595076284 |
| 20 | -6452856224076654 |
| 21 | 51760509258982478 |
| 22 | -416620859045829372 |