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 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 10 |
| 6 | 37 |
| 7 | 135 |
| 8 | 522 |
| 9 | 2060 |
| 10 | 8430 |
| 11 | 35115 |
| 12 | 149286 |
| 13 | 644456 |
| 14 | 2821835 |
| 15 | 12503878 |
| 16 | 56001856 |
| 17 | 253174451 |
| 18 | 1154179790 |
| 19 | 5301178673 |
| 20 | 24513058220 |
| 21 | 114042743290 |
| 22 | 533510321377 |
| 23 | 2508491383101 |
| 24 | 11849321038092 |
| 25 | 56211286929146 |
| 26 | 267707017974770 |
| 27 | 1279602152054934 |