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 | 15 |
| 2 | 225 |
| 3 | 1071 |
| 4 | 4743 |
| 5 | 21147 |
| 6 | 94605 |
| 7 | 422477 |
| 8 | 1889665 |
| 9 | 8446555 |
| 10 | 37743827 |
| 11 | 168707957 |
| 12 | 754104989 |
| 13 | 3370554663 |
| 14 | 15065028565 |
| 15 | 67335513723 |
| 16 | 300967334945 |
| 17 | 1345219047425 |
| 18 | 6012654700245 |
| 19 | 26874474326751 |
| 20 | 120119580310457 |
| 21 | 536892707323419 |