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 | 4 |
| 2 | 28 |
| 3 | 232 |
| 4 | 2092 |
| 5 | 19884 |
| 6 | 196096 |
| 7 | 1988424 |
| 8 | 20611116 |
| 9 | 217526524 |
| 10 | 2330681348 |
| 11 | 25296553088 |
| 12 | 277653104800 |
| 13 | 3077568629256 |
| 14 | 34410056828392 |
| 15 | 387725845018512 |
| 16 | 4399241841920428 |
| 17 | 50228061806093020 |
| 18 | 576729989899675348 |