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 | -30 |
| 2 | 435 |
| 3 | -4090 |
| 4 | 28305 |
| 5 | -155586 |
| 6 | 716910 |
| 7 | -2884080 |
| 8 | 10440930 |
| 9 | -34752790 |
| 10 | 107952705 |
| 11 | -316326840 |
| 12 | 881621260 |
| 13 | -2352438330 |
| 14 | 6041102175 |
| 15 | -14993771926 |
| 16 | 36092874960 |
| 17 | -84513784620 |
| 18 | 192981056950 |
| 19 | -430636738770 |
| 20 | 940848408276 |