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 | 7 |
| 3 | 29 |
| 4 | 153 |
| 5 | 955 |
| 6 | 6875 |
| 7 | 56145 |
| 8 | 513325 |
| 9 | 5197415 |
| 10 | 57749055 |
| 11 | 698763565 |
| 12 | 9147450305 |
| 13 | 128826591795 |
| 14 | 1942308614755 |
| 15 | 31215674165705 |
| 16 | 532747505761365 |
| 17 | 9622751822814655 |
| 18 | 183398328858349895 |
| 19 | 3678155373214684005 |
| 20 | 77434849962414400105 |
| 21 | 1707438441671237522315 |