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 | 4 |
| 3 | 8 |
| 4 | 18 |
| 5 | 56 |
| 6 | 126 |
| 7 | 630 |
| 8 | 1638 |
| 9 | 8190 |
| 10 | 31122 |
| 11 | 155610 |
| 12 | 964782 |
| 13 | 4823910 |
| 14 | 35696934 |
| 15 | 178484670 |
| 16 | 1534968162 |
| 17 | 7674840810 |
| 18 | 84423248910 |
| 19 | 468165289410 |
| 20 | 5149818183510 |
| 21 | 31367074390470 |
| 22 | 345037818295170 |
| 23 | 2289796430504310 |
| 24 | 25187760735547410 |
| 25 | 180893918009840490 |