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 | 0 |
| 1 | 3 |
| 2 | 14 |
| 3 | 58 |
| 4 | 250 |
| 5 | 994 |
| 6 | 4066 |
| 7 | 16174 |
| 8 | 65326 |
| 9 | 261934 |
| 10 | 1048366 |
| 11 | 4191994 |
| 12 | 16774906 |
| 13 | 67078834 |
| 14 | 268405426 |
| 15 | 1073711794 |
| 16 | 4294937266 |
| 17 | 17179358674 |
| 18 | 68718966226 |
| 19 | 274868207254 |
| 20 | 1099501928086 |
| 21 | 4398036811414 |
| 22 | 17592176344726 |
| 23 | 70368521084794 |
| 24 | 281474753617786 |
| 25 | 1125899683749754 |
| 26 | 4503599404277626 |