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 | 27 |
| 3 | 147 |
| 4 | 630 |
| 5 | 2295 |
| 6 | 7476 |
| 7 | 22302 |
| 8 | 62100 |
| 9 | 163260 |
| 10 | 409080 |
| 11 | 983367 |
| 12 | 2280306 |
| 13 | 5122026 |
| 14 | 11184075 |
| 15 | 23806575 |
| 16 | 49521456 |
| 17 | 100872135 |
| 18 | 201558231 |
| 19 | 395675475 |
| 20 | 764130780 |
| 21 | 1453424259 |
| 22 | 2725614243 |
| 23 | 5044092372 |
| 24 | 9219499800 |
| 25 | 16655554125 |
| 26 | 29759775435 |
| 27 | 52623867051 |