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 | 3 |
| 2 | 9 |
| 3 | 33 |
| 4 | 120 |
| 5 | 480 |
| 6 | 2079 |
| 7 | 9044 |
| 8 | 39604 |
| 9 | 170835 |
| 10 | 720348 |
| 11 | 3105394 |
| 12 | 14050148 |
| 13 | 64838808 |
| 14 | 295178921 |
| 15 | 1315098518 |
| 16 | 5765163507 |
| 17 | 25132740083 |
| 18 | 110592507674 |
| 19 | 498297998116 |
| 20 | 2314042703759 |
| 21 | 10991409243669 |
| 22 | 52236818282458 |
| 23 | 242186086327901 |