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 | 4 |
| 2 | 16 |
| 3 | 64 |
| 4 | 253 |
| 5 | 988 |
| 6 | 3816 |
| 7 | 14596 |
| 8 | 55344 |
| 9 | 208196 |
| 10 | 777582 |
| 11 | 2885120 |
| 12 | 10640607 |
| 13 | 39027196 |
| 14 | 142415244 |
| 15 | 517252820 |
| 16 | 1870499543 |
| 17 | 6736838192 |
| 18 | 24172420350 |
| 19 | 86428990624 |
| 20 | 308016010824 |
| 21 | 1094338584760 |
| 22 | 3876828265788 |
| 23 | 13696906252336 |