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 | 4 |
| 2 | 18 |
| 3 | 88 |
| 4 | 450 |
| 5 | 2344 |
| 6 | 12258 |
| 7 | 63928 |
| 8 | 331650 |
| 9 | 1710664 |
| 10 | 8776098 |
| 11 | 44810968 |
| 12 | 227894850 |
| 13 | 1155188584 |
| 14 | 5839863138 |
| 15 | 29458185208 |
| 16 | 148335970050 |
| 17 | 745888724104 |
| 18 | 3746365209378 |
| 19 | 18799770682648 |
| 20 | 94271406797250 |
| 21 | 472449572045224 |
| 22 | 2366624986030818 |
| 23 | 11850654354079288 |