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 | -1 |
| 3 | 1 |
| 4 | 2 |
| 5 | -3 |
| 6 | 1 |
| 7 | -6 |
| 8 | 11 |
| 9 | -6 |
| 10 | 1 |
| 11 | 24 |
| 12 | -50 |
| 13 | 35 |
| 14 | -10 |
| 15 | 1 |
| 16 | -120 |
| 17 | 274 |
| 18 | -225 |
| 19 | 85 |
| 20 | -15 |
| 21 | 1 |
| 22 | 720 |
| 23 | -1764 |
| 24 | 1624 |
| 25 | -735 |
| 26 | 175 |
| 27 | -21 |
| 28 | 1 |
| 29 | -5040 |
| 30 | 13068 |
| 31 | -13132 |
| 32 | 6769 |
| 33 | -1960 |
| 34 | 322 |
| 35 | -28 |
| 36 | 1 |
| 37 | 40320 |
| 38 | -109584 |
| 39 | 118124 |
| 40 | -67284 |
| 41 | 22449 |
| 42 | -4536 |
| 43 | 546 |
| 44 | -36 |
| 45 | 1 |
| 46 | -362880 |
| 47 | 1026576 |
| 48 | -1172700 |
| 49 | 723680 |
| 50 | -269325 |
| 51 | 63273 |
| 52 | -9450 |
| 53 | 870 |
| 54 | -45 |
| 55 | 1 |