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 | -5 |
| 3 | 10 |
| 4 | 20 |
| 5 | -220 |
| 6 | 624 |
| 7 | 940 |
| 8 | -15220 |
| 9 | 52090 |
| 10 | 49310 |
| 11 | -1254070 |
| 12 | 4951430 |
| 13 | 2039640 |
| 14 | -113088840 |
| 15 | 505430700 |
| 16 | -42379684 |
| 17 | -10748423405 |
| 18 | 53899438385 |
| 19 | -29300595085 |
| 20 | -1054751754795 |
| 21 | 5914944193114 |
| 22 | -5760460624890 |
| 23 | -105478270711140 |
| 24 | 661900612108440 |
| 25 | -914408777470140 |