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 | -2 |
| 2 | 5 |
| 3 | -13 |
| 4 | 33 |
| 5 | -84 |
| 6 | 214 |
| 7 | -545 |
| 8 | 1388 |
| 9 | -3535 |
| 10 | 9003 |
| 11 | -22929 |
| 12 | 58396 |
| 13 | -148724 |
| 14 | 378773 |
| 15 | -964666 |
| 16 | 2456829 |
| 17 | -6257097 |
| 18 | 15935689 |
| 19 | -40585304 |
| 20 | 103363394 |
| 21 | -263247781 |
| 22 | 670444260 |
| 23 | -1707499695 |
| 24 | 4348691431 |
| 25 | -11075326817 |
| 26 | 28206844760 |
| 27 | -71837707768 |
| 28 | 182957587113 |
| 29 | -465959726754 |