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 | 31 |
| 3 | 314 |
| 4 | 3013 |
| 5 | 27060 |
| 6 | 232671 |
| 7 | 1947118 |
| 8 | 16021801 |
| 9 | 130447976 |
| 10 | 1055068595 |
| 11 | 8498016994 |
| 12 | 68269451069 |
| 13 | 547562782044 |
| 14 | 4387403278023 |
| 15 | 35132904838614 |
| 16 | 281226897433681 |
| 17 | 2250607478637648 |
| 18 | 18008682685966299 |
| 19 | 144087851840540874 |
| 20 | 1152791046751807845 |