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 | 4 |
| 3 | 16 |
| 4 | 77 |
| 5 | 303 |
| 6 | 718 |
| 7 | -4934 |
| 8 | -108553 |
| 9 | -1275290 |
| 10 | -12473324 |
| 11 | -107472840 |
| 12 | -826679323 |
| 13 | -5418440094 |
| 14 | -24911021972 |
| 15 | 28733788740 |
| 16 | 2764189150143 |
| 17 | 48003187278203 |
| 18 | 629585195050804 |
| 19 | 7164019744705726 |
| 20 | 73396269512625553 |
| 21 | 677866973062726837 |
| 22 | 5460528984809591552 |