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 | 15 |
| 5 | -159 |
| 6 | -3021 |
| 7 | -36903 |
| 8 | -381249 |
| 9 | -3212415 |
| 10 | -12995901 |
| 11 | 315857961 |
| 12 | 12457515663 |
| 13 | 304888863969 |
| 14 | 6280156107315 |
| 15 | 113710631625081 |
| 16 | 1717208752084479 |
| 17 | 15528594345353217 |
| 18 | -265033870991715069 |
| 19 | -22048996644203788215 |