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 | 2 |
| 2 | 1 |
| 3 | -1 |
| 4 | 0 |
| 5 | 3 |
| 6 | -9 |
| 7 | 19 |
| 8 | -35 |
| 9 | 63 |
| 10 | -119 |
| 11 | 238 |
| 12 | -483 |
| 13 | 945 |
| 14 | -1715 |
| 15 | 2793 |
| 16 | -3871 |
| 17 | 3871 |
| 18 | 0 |
| 19 | -14161 |
| 20 | 52479 |
| 21 | -143717 |
| 22 | 345401 |
| 23 | -767977 |
| 24 | 1613129 |
| 25 | -3226258 |
| 26 | 6148961 |
| 27 | -11119031 |
| 28 | 18874261 |
| 29 | -29414651 |
| 30 | 39955041 |
| 31 | -39955041 |
| 32 | 0 |
| 33 | 151615947 |
| 34 | -575723785 |
| 35 | 1611404739 |
| 36 | -3936821259 |