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 | 4 |
| 2 | -6 |
| 3 | -120 |
| 4 | -266 |
| 5 | 2520 |
| 6 | 17380 |
| 7 | -13104 |
| 8 | -599130 |
| 9 | -1853544 |
| 10 | 12391116 |
| 11 | 108252144 |
| 12 | 6439356 |
| 13 | -3577917200 |
| 14 | -14043012984 |
| 15 | 65962248352 |
| 16 | 730407220998 |
| 17 | 602517029400 |
| 18 | -22507424996420 |
| 19 | -108316306187600 |
| 20 | 347406564086868 |
| 21 | 5073542740156752 |
| 22 | 7904100039294456 |
| 23 | -143838603813578400 |