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) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 27 |
| 3 | 270 |
| 4 | 2835 |
| 5 | 30618 |
| 6 | 336798 |
| 7 | 3752892 |
| 8 | 42220035 |
| 9 | 478493730 |
| 10 | 5454828522 |
| 11 | 62482581252 |
| 12 | 718549684398 |
| 13 | 8290957896900 |
| 14 | 95938227092700 |
| 15 | 1112883434275320 |
| 16 | 12937269923450595 |
| 17 | 150681143814306930 |
| 18 | 1757946677833580850 |
| 19 | 20540219077844997300 |
| 20 | 240320563210786468410 |