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 | 11 |
| 4 | 47 |
| 5 | 215 |
| 6 | 1029 |
| 7 | 5077 |
| 8 | 25615 |
| 9 | 131455 |
| 10 | 683749 |
| 11 | 3595341 |
| 12 | 19075913 |
| 13 | 101978321 |
| 14 | 548683499 |
| 15 | 2968535115 |
| 16 | 16138308655 |
| 17 | 88107960847 |
| 18 | 482839660509 |
| 19 | 2654879900085 |
| 20 | 14641704563577 |
| 21 | 80968432526961 |
| 22 | 448856443832643 |
| 23 | 2493858308981331 |
| 24 | 13884356040349161 |
| 25 | 77445573778294041 |