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 | 2 |
| 3 | 0 |
| 4 | -1 |
| 5 | -4 |
| 6 | -14 |
| 7 | -48 |
| 8 | -165 |
| 9 | -572 |
| 10 | -2002 |
| 11 | -7072 |
| 12 | -25194 |
| 13 | -90440 |
| 14 | -326876 |
| 15 | -1188640 |
| 16 | -4345965 |
| 17 | -15967980 |
| 18 | -58929450 |
| 19 | -218349120 |
| 20 | -811985790 |
| 21 | -3029594040 |
| 22 | -11338026180 |
| 23 | -42550029600 |
| 24 | -160094486370 |
| 25 | -603784920024 |
| 26 | -2282138106804 |
| 27 | -8643460269248 |
| 28 | -32798844771700 |