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 | 5 |
| 3 | 29 |
| 4 | 189 |
| 5 | 1325 |
| 6 | 9757 |
| 7 | 74429 |
| 8 | 583037 |
| 9 | 4662653 |
| 10 | 37911037 |
| 11 | 312457469 |
| 12 | 2604534269 |
| 13 | 21919435517 |
| 14 | 185992729085 |
| 15 | 1589480795133 |
| 16 | 13668519794685 |
| 17 | 118188894992381 |
| 18 | 1026965424910333 |
| 19 | 8962634482450429 |
| 20 | 78528344593006589 |
| 21 | 690502653622083581 |