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 | 2 |
| 2 | 5 |
| 3 | 18 |
| 4 | 93 |
| 5 | 634 |
| 6 | 5317 |
| 7 | 52610 |
| 8 | 598445 |
| 9 | 7685706 |
| 10 | 109933269 |
| 11 | 1732565842 |
| 12 | 29824133437 |
| 13 | 556682481818 |
| 14 | 11198025452261 |
| 15 | 241481216430114 |
| 16 | 5557135898411469 |
| 17 | 135927902927547370 |
| 18 | 3521462566184392693 |
| 19 | 96323049885512803826 |
| 20 | 2774010846129897006941 |
| 21 | 83898835844633970888762 |