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 | 2 |
| 3 | 8 |
| 4 | 42 |
| 5 | 272 |
| 6 | 2115 |
| 7 | 19010 |
| 8 | 192760 |
| 9 | 2172468 |
| 10 | 26896081 |
| 11 | 362184998 |
| 12 | 5262526484 |
| 13 | 81969555736 |
| 14 | 1361249430071 |
| 15 | 23989460080079 |
| 16 | 446832403813788 |
| 17 | 8765575657218860 |
| 18 | 180544405959236487 |
| 19 | 3893718987163468969 |
| 20 | 87711985393624557487 |
| 21 | 2059264143275898894916 |