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 | 2 |
| 5 | 6 |
| 6 | -18 |
| 7 | -6 |
| 8 | 114 |
| 9 | -146 |
| 10 | -490 |
| 11 | 1794 |
| 12 | 266 |
| 13 | -12986 |
| 14 | 20958 |
| 15 | 56778 |
| 16 | -255774 |
| 17 | 39390 |
| 18 | 1853478 |
| 19 | -3687918 |
| 20 | -7441158 |
| 21 | 42252726 |
| 22 | -20345490 |
| 23 | -293463462 |
| 24 | 708206802 |
| 25 | 1002083406 |
| 26 | -7527677898 |
| 27 | 6140678434 |
| 28 | 48978210794 |
| 29 | -142206136026 |
| 30 | -127715768578 |