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 | 73 |
| 3 | 730 |
| 4 | 5185 |
| 5 | 30376 |
| 6 | 157465 |
| 7 | 750142 |
| 8 | 3359233 |
| 9 | 14348908 |
| 10 | 59049001 |
| 11 | 235782658 |
| 12 | 918330049 |
| 13 | 3502727632 |
| 14 | 13124466937 |
| 15 | 48427561126 |
| 16 | 176319369217 |
| 17 | 634465620820 |
| 18 | 2259436291849 |
| 19 | 7971951402154 |
| 20 | 27894275208001 |
| 21 | 96873331012984 |