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 | 171 |
| 4 | 855 |
| 5 | 2421 |
| 6 | 9801 |
| 7 | 31419 |
| 8 | 116919 |
| 9 | 394965 |
| 10 | 1419849 |
| 11 | 4902939 |
| 12 | 17375031 |
| 13 | 60551541 |
| 14 | 213310665 |
| 15 | 746231931 |
| 16 | 2622329271 |
| 17 | 9188418069 |
| 18 | 32255749449 |
| 19 | 113096449755 |
| 20 | 396852637239 |
| 21 | 1391845926069 |
| 22 | 4883081614281 |
| 23 | 17127968887611 |