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 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 22 |
| 7 | 59 |
| 8 | 170 |
| 9 | 516 |
| 10 | 1658 |
| 11 | 5583 |
| 12 | 19683 |
| 13 | 72162 |
| 14 | 274796 |
| 15 | 1082439 |
| 16 | 4406706 |
| 17 | 18484332 |
| 18 | 79818616 |
| 19 | 353995743 |
| 20 | 1611041726 |
| 21 | 7510754022 |
| 22 | 35842380314 |
| 23 | 174850257639 |
| 24 | 871343536591 |
| 25 | 4430997592209 |
| 26 | 22978251206350 |
| 27 | 121410382810005 |
| 28 | 653225968918521 |