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 | 0 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 50 |
| 6 | 180 |
| 7 | 695 |
| 8 | 2869 |
| 9 | 12616 |
| 10 | 58862 |
| 11 | 290305 |
| 12 | 1508483 |
| 13 | 8233942 |
| 14 | 47086560 |
| 15 | 281420499 |
| 16 | 1753994617 |
| 17 | 11377449948 |
| 18 | 76667702218 |
| 19 | 535802458029 |
| 20 | 3877528409495 |
| 21 | 29016786672794 |
| 22 | 224243915547756 |
| 23 | 1787491551588239 |
| 24 | 14680196745177309 |
| 25 | 124088256248966864 |
| 26 | 1078492866534953734 |