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 | 5 |
| 3 | -14 |
| 4 | 36 |
| 5 | -97 |
| 6 | 246 |
| 7 | -593 |
| 8 | 1423 |
| 9 | -3351 |
| 10 | 7699 |
| 11 | -17432 |
| 12 | 38901 |
| 13 | -85545 |
| 14 | 185862 |
| 15 | -399220 |
| 16 | 848080 |
| 17 | -1783682 |
| 18 | 3716584 |
| 19 | -7675916 |
| 20 | 15722127 |
| 21 | -31951330 |
| 22 | 64452707 |
| 23 | -129102947 |
| 24 | 256876062 |
| 25 | -507854808 |
| 26 | 997954125 |
| 27 | -1949631802 |
| 28 | 3787674152 |
| 29 | -7319306458 |
| 30 | 14071371173 |