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 | 1 |
| 2 | 1 |
| 3 | -5 |
| 4 | -23 |
| 5 | -59 |
| 6 | 601 |
| 7 | 4831 |
| 8 | 19825 |
| 9 | -302903 |
| 10 | -3478319 |
| 11 | -19626749 |
| 12 | 399831961 |
| 13 | 5968795405 |
| 14 | 42864819817 |
| 15 | -1091541253529 |
| 16 | -20055152560799 |
| 17 | -174888464853359 |
| 18 | 5344185977277985 |
| 19 | 116600656988485387 |
| 20 | 1196237099596975561 |
| 21 | -42646604098678320299 |
| 22 | -1077390070573604975879 |