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 | -4 |
| 2 | -9 |
| 3 | -19 |
| 4 | -9 |
| 5 | 317 |
| 6 | 3351 |
| 7 | 26141 |
| 8 | 183111 |
| 9 | 1216637 |
| 10 | 7842231 |
| 11 | 49591901 |
| 12 | 309595431 |
| 13 | 1915328957 |
| 14 | 11771279511 |
| 15 | 71987413661 |
| 16 | 438579282951 |
| 17 | 2664183937277 |
| 18 | 16146410851191 |
| 19 | 97676152243421 |
| 20 | 590010212989671 |
| 21 | 3559688008961597 |