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 | 2 |
| 3 | 1 |
| 4 | -4 |
| 5 | -14 |
| 6 | -30 |
| 7 | 12 |
| 8 | 330 |
| 9 | 1139 |
| 10 | 2226 |
| 11 | -2288 |
| 12 | -39646 |
| 13 | -163742 |
| 14 | -410900 |
| 15 | -89273 |
| 16 | 5352720 |
| 17 | 31177720 |
| 18 | 114624554 |
| 19 | 234094417 |
| 20 | -312845870 |
| 21 | -5584935715 |
| 22 | -32878240028 |
| 23 | -127407695297 |
| 24 | -315375599410 |
| 25 | 24759230680 |
| 26 | 6177102106748 |
| 27 | 44838273448641 |
| 28 | 220383314338200 |