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 | -9 |
| 3 | 0 |
| 4 | 81 |
| 5 | 18 |
| 6 | 0 |
| 7 | 36 |
| 8 | -729 |
| 9 | 0 |
| 10 | -162 |
| 11 | 72 |
| 12 | 0 |
| 13 | 90 |
| 14 | -324 |
| 15 | 0 |
| 16 | 6561 |
| 17 | 126 |
| 18 | 0 |
| 19 | 144 |
| 20 | 1458 |
| 21 | 0 |
| 22 | -648 |
| 23 | 180 |
| 24 | 0 |
| 25 | 324 |
| 26 | -810 |
| 27 | 0 |
| 28 | 2916 |
| 29 | 234 |
| 30 | 0 |
| 31 | 252 |
| 32 | -59049 |
| 33 | 0 |
| 34 | -1134 |
| 35 | 648 |
| 36 | 0 |
| 37 | 306 |
| 38 | -1296 |
| 39 | 0 |
| 40 | -13122 |
| 41 | 342 |
| 42 | 0 |
| 43 | 360 |
| 44 | 5832 |
| 45 | 0 |
| 46 | -1620 |
| 47 | 396 |
| 48 | 0 |
| 49 | 1296 |
| 50 | -2916 |
| 51 | 0 |
| 52 | 7290 |
| 53 | 450 |
| 54 | 0 |
| 55 | 1296 |
| 56 | -26244 |