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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 5 |
| 5 | 15 |
| 6 | 55 |
| 7 | 210 |
| 8 | 826 |
| 9 | 3306 |
| 10 | 13511 |
| 11 | 55922 |
| 12 | 234344 |
| 13 | 991701 |
| 14 | 4233301 |
| 15 | 18204973 |
| 16 | 78803016 |
| 17 | 343074124 |
| 18 | 1501253960 |
| 19 | 6599380039 |
| 20 | 29129716885 |
| 21 | 129056936567 |
| 22 | 573707565933 |
| 23 | 2558203198595 |
| 24 | 11439372705501 |
| 25 | 51285319846823 |
| 26 | 230473042074581 |
| 27 | 1038019965961144 |