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 | 9 |
| 2 | 63 |
| 3 | 354 |
| 4 | 1755 |
| 5 | 7866 |
| 6 | 32682 |
| 7 | 127458 |
| 8 | 471681 |
| 9 | 1668313 |
| 10 | 5673501 |
| 11 | 18635229 |
| 12 | 59342520 |
| 13 | 183768255 |
| 14 | 554843493 |
| 15 | 1636855647 |
| 16 | 4727195028 |
| 17 | 13386032649 |
| 18 | 37219413972 |
| 19 | 101741003451 |
| 20 | 273721954086 |
| 21 | 725498278359 |
| 22 | 1896086574252 |
| 23 | 4890111992460 |
| 24 | 12454590256587 |