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) |
|---|---|
| 3 | 1 |
| 4 | 11 |
| 5 | 66 |
| 6 | 302 |
| 7 | 1191 |
| 8 | 4293 |
| 9 | 14608 |
| 10 | 47840 |
| 11 | 152637 |
| 12 | 478271 |
| 13 | 1479726 |
| 14 | 4537314 |
| 15 | 13824739 |
| 16 | 41932745 |
| 17 | 126781020 |
| 18 | 382439924 |
| 19 | 1151775897 |
| 20 | 3464764515 |
| 21 | 10414216090 |
| 22 | 31284590870 |
| 23 | 93941852511 |
| 24 | 282010106381 |
| 25 | 846416194536 |
| 26 | 2540053889352 |
| 27 | 7621839388981 |
| 28 | 22869007827143 |