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) |
|---|---|
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 21 |
| 6 | 89 |
| 7 | 340 |
| 8 | 1312 |
| 9 | 5106 |
| 10 | 19782 |
| 11 | 76676 |
| 12 | 297776 |
| 13 | 1157609 |
| 14 | 4505193 |
| 15 | 17554888 |
| 16 | 68480902 |
| 17 | 267420957 |
| 18 | 1045329995 |
| 19 | 4089922224 |
| 20 | 16015961548 |
| 21 | 62768643959 |
| 22 | 246184737835 |
| 23 | 966243694608 |
| 24 | 3794894344275 |
| 25 | 14913585439328 |