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) |
|---|---|
| 1 | 1 |
| 2 | -3 |
| 3 | 9 |
| 4 | -22 |
| 5 | 51 |
| 6 | -108 |
| 7 | 221 |
| 8 | -429 |
| 9 | 810 |
| 10 | -1476 |
| 11 | 2631 |
| 12 | -4572 |
| 13 | 7802 |
| 14 | -13056 |
| 15 | 21519 |
| 16 | -34918 |
| 17 | 55935 |
| 18 | -88452 |
| 19 | 138332 |
| 20 | -213990 |
| 21 | 327852 |
| 22 | -497592 |
| 23 | 748833 |
| 24 | -1117692 |
| 25 | 1655719 |
| 26 | -2434938 |
| 27 | 3556791 |
| 28 | -5161808 |
| 29 | 7445631 |
| 30 | -10677096 |
| 31 | 15226658 |
| 32 | -21599469 |
| 33 | 30485268 |
| 34 | -42817788 |