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 | 2 |
| 1 | 7 |
| 2 | 31 |
| 3 | 145 |
| 4 | 701 |
| 5 | 3458 |
| 6 | 17298 |
| 7 | 87417 |
| 8 | 445225 |
| 9 | 2281565 |
| 10 | 11750245 |
| 11 | 60763950 |
| 12 | 315315014 |
| 13 | 1641046720 |
| 14 | 8562466432 |
| 15 | 44775095601 |
| 16 | 234594444741 |
| 17 | 1231249999640 |
| 18 | 6472043549400 |
| 19 | 34067089542255 |
| 20 | 179543120927115 |