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 | 7 |
| 2 | 56 |
| 3 | 399 |
| 4 | 2849 |
| 5 | 19999 |
| 6 | 140441 |
| 7 | 983535 |
| 8 | 6887986 |
| 9 | 48219486 |
| 10 | 337559586 |
| 11 | 2362943030 |
| 12 | 16540767131 |
| 13 | 115785555389 |
| 14 | 810500055939 |
| 15 | 5673501716540 |
| 16 | 39714520225149 |
| 17 | 278001650902563 |
| 18 | 1946011613977669 |
| 19 | 13622081363362570 |
| 20 | 95354569947550935 |
| 21 | 667481990092883448 |