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 | 3 |
| 3 | 9 |
| 4 | 39 |
| 5 | 153 |
| 6 | 543 |
| 7 | 1809 |
| 8 | 5799 |
| 9 | 18153 |
| 10 | 55983 |
| 11 | 171009 |
| 12 | 519159 |
| 13 | 1569753 |
| 14 | 4733823 |
| 15 | 14250609 |
| 16 | 42850119 |
| 17 | 128746953 |
| 18 | 386634063 |
| 19 | 1160688609 |
| 20 | 3483638679 |
| 21 | 10454061753 |
| 22 | 31368476703 |
| 23 | 94118013009 |
| 24 | 282379204839 |
| 25 | 847187946153 |
| 26 | 2541664501743 |
| 27 | 7625194831809 |
| 28 | 22875987148599 |
| 29 | 68628766752153 |
| 30 | 205887910869183 |
| 31 | 617666953833009 |