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 | 0 |
| 1 | -2 |
| 2 | -3 |
| 3 | 6 |
| 4 | 20 |
| 5 | -5 |
| 6 | -105 |
| 7 | -98 |
| 8 | 420 |
| 9 | 1008 |
| 10 | -990 |
| 11 | -6501 |
| 12 | -2574 |
| 13 | 31603 |
| 14 | 52052 |
| 15 | -107250 |
| 16 | -411944 |
| 17 | 81328 |
| 18 | 2343042 |
| 19 | 2413456 |
| 20 | -9883800 |
| 21 | -25327722 |
| 22 | 23371634 |
| 23 | 168185131 |
| 24 | 77113020 |
| 25 | -835281800 |
| 26 | -1452148815 |
| 27 | 2847865635 |
| 28 | 11561517870 |
| 29 | -1613666430 |
| 30 | -66318892875 |
| 31 | -72637680690 |
| 32 | 280330495200 |
| 33 | 750725215020 |