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 | 12 |
| 3 | 39 |
| 4 | 129 |
| 5 | 453 |
| 6 | 1677 |
| 7 | 6429 |
| 8 | 25149 |
| 9 | 99453 |
| 10 | 395517 |
| 11 | 1577469 |
| 12 | 6300669 |
| 13 | 25184253 |
| 14 | 100700157 |
| 15 | 402726909 |
| 16 | 1610760189 |
| 17 | 6442745853 |
| 18 | 25770393597 |
| 19 | 103080394749 |
| 20 | 412319219709 |
| 21 | 1649272160253 |
| 22 | 6597079203837 |
| 23 | 26388297940989 |
| 24 | 105553154015229 |
| 25 | 422212540563453 |
| 26 | 1688850011258877 |
| 27 | 6755399743045629 |