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 | 7 |
| 2 | 45 |
| 3 | 286 |
| 4 | 2520 |
| 5 | 20122 |
| 6 | 148148 |
| 7 | 1007606 |
| 8 | 6254640 |
| 9 | 46181513 |
| 10 | 391594275 |
| 11 | 3034699661 |
| 12 | 21731298679 |
| 13 | 143399099473 |
| 14 | 855828562635 |
| 15 | 7344390292954 |
| 16 | 60173627260320 |
| 17 | 453178096117918 |
| 18 | 3155291100853892 |
| 19 | 20155636317704834 |
| 20 | 131804682060038201 |
| 21 | 1152529734625490207 |