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 | 0 |
| 1 | 3 |
| 2 | 18 |
| 3 | 111 |
| 4 | 750 |
| 5 | 5403 |
| 6 | 40572 |
| 7 | 313407 |
| 8 | 2471166 |
| 9 | 19791003 |
| 10 | 160459068 |
| 11 | 1313922063 |
| 12 | 10847561088 |
| 13 | 90174127683 |
| 14 | 754009158018 |
| 15 | 6336733626111 |
| 16 | 53489159252670 |
| 17 | 453258909448635 |
| 18 | 3854034482891724 |
| 19 | 32871004555812111 |
| 20 | 281127047928811200 |
| 21 | 2410285909684370787 |
| 22 | 20711470169495359602 |
| 23 | 178337708176330555839 |