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 | 2 |
| 3 | 0 |
| 4 | -6 |
| 5 | 12 |
| 6 | 67 |
| 7 | -152 |
| 8 | -740 |
| 9 | 2296 |
| 10 | 9017 |
| 11 | -35979 |
| 12 | -113936 |
| 13 | 579516 |
| 14 | 1454975 |
| 15 | -9493390 |
| 16 | -18317155 |
| 17 | 157178640 |
| 18 | 220172289 |
| 19 | -2618995381 |
| 20 | -2377680689 |
| 21 | 43783556265 |
| 22 | 19149194005 |
| 23 | -732638868460 |
| 24 | 16196837316 |
| 25 | 12246524817736 |
| 26 | -5891297294673 |