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 | 3 |
| 1 | 12 |
| 2 | 43 |
| 3 | 147 |
| 4 | 486 |
| 5 | 1566 |
| 6 | 4944 |
| 7 | 15351 |
| 8 | 47009 |
| 9 | 142278 |
| 10 | 426315 |
| 11 | 1266300 |
| 12 | 3732705 |
| 13 | 10928910 |
| 14 | 31806583 |
| 15 | 92069229 |
| 16 | 265215756 |
| 17 | 760621914 |
| 18 | 2172669846 |
| 19 | 6183333681 |
| 20 | 17538237677 |
| 21 | 49590486888 |
| 22 | 139817553417 |
| 23 | 393157465848 |
| 24 | 1102792703055 |
| 25 | 3086146454592 |
| 26 | 8617872504643 |