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 | 9 |
| 2 | 81 |
| 3 | 281 |
| 4 | 981 |
| 5 | 3893 |
| 6 | 13825 |
| 7 | 46611 |
| 8 | 159545 |
| 9 | 538479 |
| 10 | 1783379 |
| 11 | 5887303 |
| 12 | 19371713 |
| 13 | 63378811 |
| 14 | 206749703 |
| 15 | 673357733 |
| 16 | 2188957835 |
| 17 | 7106004543 |
| 18 | 23048741587 |
| 19 | 74706706363 |
| 20 | 242002483927 |
| 21 | 783622093421 |
| 22 | 2536664872659 |
| 23 | 8209475506107 |