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 | 0 |
| 3 | -2 |
| 4 | -1 |
| 5 | 12 |
| 6 | 20 |
| 7 | -113 |
| 8 | -430 |
| 9 | 1278 |
| 10 | 10821 |
| 11 | -10234 |
| 12 | -317048 |
| 13 | -384915 |
| 14 | 10352420 |
| 15 | 42836466 |
| 16 | -340348905 |
| 17 | -3180089128 |
| 18 | 8045616512 |
| 19 | 219303897655 |
| 20 | 301713947470 |
| 21 | -14401913182942 |
| 22 | -84197219028827 |
| 23 | 824481606288554 |
| 24 | 11426928115546036 |
| 25 | -23133559937561187 |