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 | 2 |
| 2 | 9 |
| 3 | 24 |
| 4 | 90 |
| 5 | 258 |
| 6 | 1043 |
| 7 | 3440 |
| 8 | 13419 |
| 9 | 48850 |
| 10 | 187836 |
| 11 | 705444 |
| 12 | 2725099 |
| 13 | 10400614 |
| 14 | 40233015 |
| 15 | 155133856 |
| 16 | 601820876 |
| 17 | 2333606238 |
| 18 | 9079958260 |
| 19 | 35345263820 |
| 20 | 137876637843 |
| 21 | 538259060526 |
| 22 | 2104292500739 |
| 23 | 8233430727624 |
| 24 | 32248866496625 |
| 25 | 126410606580284 |