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 | 1 |
| 2 | 3 |
| 3 | 19 |
| 4 | 139 |
| 5 | 1097 |
| 6 | 8960 |
| 7 | 75290 |
| 8 | 651085 |
| 9 | 5735086 |
| 10 | 51247361 |
| 11 | 463196868 |
| 12 | 4225763390 |
| 13 | 38851672813 |
| 14 | 359541975662 |
| 15 | 3345924530873 |
| 16 | 31288310624754 |
| 17 | 293820812588401 |
| 18 | 2769490109678920 |
| 19 | 26191046215879444 |
| 20 | 248421640738371325 |
| 21 | 2362546444095790527 |
| 22 | 22522418647770393663 |