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 | 1 |
| 5 | 1 |
| 6 | -1 |
| 7 | -3 |
| 8 | 4 |
| 9 | 8 |
| 10 | -13 |
| 11 | -23 |
| 12 | 39 |
| 13 | 71 |
| 14 | -121 |
| 15 | -229 |
| 16 | 400 |
| 17 | 757 |
| 18 | -1354 |
| 19 | -2559 |
| 20 | 4625 |
| 21 | 8799 |
| 22 | -16021 |
| 23 | -30671 |
| 24 | 56316 |
| 25 | 108166 |
| 26 | -200047 |
| 27 | -385210 |
| 28 | 716429 |
| 29 | 1383331 |
| 30 | -2585173 |
| 31 | -5003791 |
| 32 | 9391680 |
| 33 | 18214565 |
| 34 | -34318117 |
| 35 | -66674463 |
| 36 | 126044208 |
| 37 | 245273927 |
| 38 | -465067981 |