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) |
|---|---|
| 0 | 1 |
| 1 | 25 |
| 2 | 381 |
| 3 | 4585 |
| 4 | 47978 |
| 5 | 458010 |
| 6 | 4100370 |
| 7 | 35027850 |
| 8 | 288845370 |
| 9 | 2317794050 |
| 10 | 18203687502 |
| 11 | 140533725150 |
| 12 | 1069904389008 |
| 13 | 8052575725680 |
| 14 | 60033791987424 |
| 15 | 444015014417280 |
| 16 | 3261950250436845 |
| 17 | 23827019766988725 |
| 18 | 173193081555808545 |
| 19 | 1253583401573658925 |
| 20 | 9040278899072328006 |