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 | 6 |
| 2 | 36 |
| 3 | 102 |
| 4 | 378 |
| 5 | 1260 |
| 6 | 4374 |
| 7 | 14946 |
| 8 | 51384 |
| 9 | 176238 |
| 10 | 605022 |
| 11 | 2076288 |
| 12 | 7126302 |
| 13 | 24457806 |
| 14 | 83942100 |
| 15 | 288096942 |
| 16 | 988778082 |
| 17 | 3393583068 |
| 18 | 11647114446 |
| 19 | 39974047290 |
| 20 | 137194888728 |
| 21 | 470866430838 |
| 22 | 1616060190870 |
| 23 | 5546478488640 |