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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 21 |
| 5 | 79 |
| 6 | 281 |
| 7 | 963 |
| 8 | 3217 |
| 9 | 10547 |
| 10 | 34089 |
| 11 | 108955 |
| 12 | 345137 |
| 13 | 1085331 |
| 14 | 3392377 |
| 15 | 10549739 |
| 16 | 32667201 |
| 17 | 100782787 |
| 18 | 309946697 |
| 19 | 950599131 |
| 20 | 2908512145 |
| 21 | 8880484019 |
| 22 | 27064776729 |
| 23 | 82350874699 |
| 24 | 250212362465 |
| 25 | 759269653155 |
| 26 | 2301393567721 |
| 27 | 6968615051195 |