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 | 1 |
| 2 | 3 |
| 3 | -1 |
| 4 | 9 |
| 5 | -4 |
| 6 | 27 |
| 7 | -15 |
| 8 | 1 |
| 9 | 81 |
| 10 | -54 |
| 11 | 7 |
| 12 | 243 |
| 13 | -189 |
| 14 | 36 |
| 15 | -1 |
| 16 | 729 |
| 17 | -648 |
| 18 | 162 |
| 19 | -10 |
| 20 | 2187 |
| 21 | -2187 |
| 22 | 675 |
| 23 | -66 |
| 24 | 1 |
| 25 | 6561 |
| 26 | -7290 |
| 27 | 2673 |
| 28 | -360 |
| 29 | 13 |
| 30 | 19683 |
| 31 | -24057 |
| 32 | 10206 |
| 33 | -1755 |
| 34 | 105 |
| 35 | -1 |
| 36 | 59049 |
| 37 | -78732 |
| 38 | 37908 |
| 39 | -7938 |
| 40 | 675 |
| 41 | -16 |