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 | 6 |
| 3 | 12 |
| 4 | -122 |
| 5 | -316 |
| 6 | 4124 |
| 7 | 11608 |
| 8 | -169018 |
| 9 | -495724 |
| 10 | 7676596 |
| 11 | 23075112 |
| 12 | -371737956 |
| 13 | -1135805144 |
| 14 | 18808209528 |
| 15 | 58139400112 |
| 16 | -982459035322 |
| 17 | -3063548374604 |
| 18 | 52579900855620 |
| 19 | 165071778169864 |
| 20 | -2868211199377740 |
| 21 | -9053503669975944 |