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 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 115 |
| 5 | 1021 |
| 6 | 10696 |
| 7 | 128472 |
| 8 | 1734447 |
| 9 | 25937683 |
| 10 | 424852351 |
| 11 | 7554471156 |
| 12 | 144767131444 |
| 13 | 2971727661124 |
| 14 | 65013102375404 |
| 15 | 1509186299410896 |
| 16 | 37032678328740751 |
| 17 | 957376811266995031 |
| 18 | 25999194631060525009 |
| 19 | 739741591417352081464 |
| 20 | 22000132609456951524051 |