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 | -5 |
| 2 | 5 |
| 3 | 0 |
| 4 | 0 |
| 5 | -1 |
| 6 | -5 |
| 7 | -20 |
| 8 | -75 |
| 9 | -275 |
| 10 | -1001 |
| 11 | -3640 |
| 12 | -13260 |
| 13 | -48450 |
| 14 | -177650 |
| 15 | -653752 |
| 16 | -2414425 |
| 17 | -8947575 |
| 18 | -33266625 |
| 19 | -124062000 |
| 20 | -463991880 |
| 21 | -1739969550 |
| 22 | -6541168950 |
| 23 | -24647883000 |
| 24 | -93078189750 |
| 25 | -352207870014 |
| 26 | -1335293573130 |
| 27 | -5071418015120 |
| 28 | -19293438101000 |