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 | 13 |
| 3 | 113 |
| 4 | 785 |
| 5 | 4755 |
| 6 | 26163 |
| 7 | 134164 |
| 8 | 651814 |
| 9 | 3035018 |
| 10 | 13657458 |
| 11 | 59769854 |
| 12 | 255628486 |
| 13 | 1072565093 |
| 14 | 4428689165 |
| 15 | 18041493575 |
| 16 | 72667375995 |
| 17 | 289905733805 |
| 18 | 1147339718965 |
| 19 | 4510476836460 |
| 20 | 17634066423470 |
| 21 | 68632042506612 |