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 | 4 |
| 2 | 15 |
| 3 | 56 |
| 4 | 126 |
| 5 | 252 |
| 6 | 924 |
| 7 | 3432 |
| 8 | 6435 |
| 9 | 11440 |
| 10 | 43758 |
| 11 | 167960 |
| 12 | 293930 |
| 13 | 497420 |
| 14 | 1961256 |
| 15 | 3268760 |
| 16 | 5311735 |
| 17 | 8436285 |
| 18 | 13123110 |
| 19 | 54627300 |
| 20 | 225792840 |
| 21 | 354817320 |
| 22 | 548354040 |
| 23 | 834451800 |
| 24 | 1251677700 |
| 25 | 5414950296 |
| 26 | 8122425444 |
| 27 | 12033222880 |