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 | 0 |
| 2 | -5 |
| 3 | -25 |
| 4 | -100 |
| 5 | -375 |
| 6 | -1375 |
| 7 | -5000 |
| 8 | -18125 |
| 9 | -65625 |
| 10 | -237500 |
| 11 | -859375 |
| 12 | -3109375 |
| 13 | -11250000 |
| 14 | -40703125 |
| 15 | -147265625 |
| 16 | -532812500 |
| 17 | -1927734375 |
| 18 | -6974609375 |
| 19 | -25234375000 |
| 20 | -91298828125 |
| 21 | -330322265625 |
| 22 | -1195117187500 |
| 23 | -4323974609375 |
| 24 | -15644287109375 |
| 25 | -56601562500000 |