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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 50 |
| 5 | 310 |
| 6 | 2056 |
| 7 | 14273 |
| 8 | 102410 |
| 9 | 753390 |
| 10 | 5651948 |
| 11 | 43074218 |
| 12 | 332553252 |
| 13 | 2595442616 |
| 14 | 20443630100 |
| 15 | 162308182577 |
| 16 | 1297503030106 |
| 17 | 10435055801110 |
| 18 | 84371602316812 |
| 19 | 685424273207630 |
| 20 | 5592040955107420 |
| 21 | 45798007929729828 |