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 | 4 |
| 3 | 15 |
| 4 | 61 |
| 5 | 272 |
| 6 | 1317 |
| 7 | 6865 |
| 8 | 38278 |
| 9 | 227093 |
| 10 | 1426921 |
| 11 | 9457918 |
| 12 | 65898275 |
| 13 | 481177881 |
| 14 | 3672102116 |
| 15 | 29218285875 |
| 16 | 241873478425 |
| 17 | 2079079678176 |
| 18 | 18524191138689 |
| 19 | 170803860905237 |
| 20 | 1627465240969382 |