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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 30 |
| 5 | 186 |
| 6 | 1164 |
| 7 | 7344 |
| 8 | 46732 |
| 9 | 299604 |
| 10 | 1932900 |
| 11 | 12537542 |
| 12 | 81705782 |
| 13 | 534663812 |
| 14 | 3511466838 |
| 15 | 23136724382 |
| 16 | 152888000934 |
| 17 | 1012925595468 |
| 18 | 6726766841438 |
| 19 | 44767880394634 |
| 20 | 298522284224824 |
| 21 | 1994187071224056 |
| 22 | 13343458013982572 |
| 23 | 89420609914983270 |
| 24 | 600088861692380354 |
| 25 | 4032377457462571694 |
| 26 | 27129080022839863318 |
| 27 | 182726605700552001998 |