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 | 4 |
| 2 | 18 |
| 3 | 112 |
| 4 | 847 |
| 5 | 7086 |
| 6 | 62974 |
| 7 | 583002 |
| 8 | 5560323 |
| 9 | 54249583 |
| 10 | 538873135 |
| 11 | 5431177821 |
| 12 | 55402340842 |
| 13 | 570899082760 |
| 14 | 5933922697380 |
| 15 | 62138800690564 |
| 16 | 654949976467593 |
| 17 | 6942859160218698 |
| 18 | 73972792893687427 |
| 19 | 791722414873487767 |
| 20 | 8508265804914763731 |