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 | -1 |
| 3 | 4 |
| 4 | -6 |
| 5 | 16 |
| 6 | -17 |
| 7 | 34 |
| 8 | -24 |
| 9 | 84 |
| 10 | -98 |
| 11 | 273 |
| 12 | -194 |
| 13 | 449 |
| 14 | -209 |
| 15 | 1089 |
| 16 | -726 |
| 17 | 2695 |
| 18 | -1295 |
| 19 | 5049 |
| 20 | -990 |
| 21 | 10044 |
| 22 | -3125 |
| 23 | 23335 |
| 24 | -2936 |
| 25 | 40516 |
| 26 | 3052 |
| 27 | 82874 |
| 28 | 3553 |
| 29 | 171086 |
| 30 | 25168 |
| 31 | 307395 |
| 32 | 104259 |
| 33 | 577831 |
| 34 | 206819 |
| 35 | 1149058 |
| 36 | 488114 |
| 37 | 2030380 |
| 38 | 1156155 |
| 39 | 3805389 |
| 40 | 2233077 |
| 41 | 7109113 |