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 | 3 |
| 3 | 14 |
| 4 | 81 |
| 5 | 538 |
| 6 | 3926 |
| 7 | 30694 |
| 8 | 252939 |
| 9 | 2172830 |
| 10 | 19304190 |
| 11 | 176343390 |
| 12 | 1649008456 |
| 13 | 15730575554 |
| 14 | 152663683494 |
| 15 | 1503962954930 |
| 16 | 15012865733351 |
| 17 | 151622652413194 |
| 18 | 1547365078534578 |
| 19 | 15939972379349178 |
| 20 | 165597452660771610 |
| 21 | 1733609081727968492 |