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 | 2 |
| 2 | 5 |
| 3 | 12 |
| 4 | 22 |
| 5 | 0 |
| 6 | -284 |
| 7 | -1938 |
| 8 | -9367 |
| 9 | -36938 |
| 10 | -118105 |
| 11 | -260130 |
| 12 | 56637 |
| 13 | 4890560 |
| 14 | 35945616 |
| 15 | 186674620 |
| 16 | 782890326 |
| 17 | 2632462236 |
| 18 | 5987222046 |
| 19 | -2241224328 |
| 20 | -129137211280 |
| 21 | -967479390360 |
| 22 | -5145272296080 |
| 23 | -22060975744080 |
| 24 | -75535676951124 |
| 25 | -172915138783080 |