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 | 3 |
| 2 | 9 |
| 3 | 31 |
| 4 | 121 |
| 5 | 515 |
| 6 | 2321 |
| 7 | 10879 |
| 8 | 52465 |
| 9 | 258563 |
| 10 | 1296281 |
| 11 | 6589727 |
| 12 | 33887465 |
| 13 | 175966211 |
| 14 | 921353249 |
| 15 | 4858956287 |
| 16 | 25786112993 |
| 17 | 137604139011 |
| 18 | 737922992937 |
| 19 | 3974647310111 |
| 20 | 21493266631001 |
| 21 | 116642921832963 |
| 22 | 635074797251889 |
| 23 | 3467998148181631 |
| 24 | 18989465797056721 |
| 25 | 104239408386028035 |