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 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 108 |
| 5 | 1032 |
| 6 | 12388 |
| 7 | 179572 |
| 8 | 3052986 |
| 9 | 59555338 |
| 10 | 1310677726 |
| 11 | 32114051862 |
| 12 | 866766965308 |
| 13 | 25547102523604 |
| 14 | 816335926158372 |
| 15 | 28107705687291892 |
| 16 | 1037367351120788551 |
| 17 | 40852168787823027351 |
| 18 | 1709792654612819858341 |