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 | -1 |
| 4 | -5 |
| 5 | -11 |
| 6 | -7 |
| 7 | 31 |
| 8 | 139 |
| 9 | 245 |
| 10 | -71 |
| 11 | -1937 |
| 12 | -5989 |
| 13 | -6251 |
| 14 | 25945 |
| 15 | 144479 |
| 16 | 304843 |
| 17 | -177899 |
| 18 | -3517351 |
| 19 | -11743505 |
| 20 | -10097381 |
| 21 | 81902453 |
| 22 | 433558201 |
| 23 | 840235039 |
| 24 | -1481279605 |
| 25 | -15839941451 |
| 26 | -48073840007 |
| 27 | -8454966289 |
| 28 | 564429256219 |
| 29 | 2518098130645 |
| 30 | 3490609807769 |