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 | 19 |
| 3 | 103 |
| 4 | 622 |
| 5 | 4117 |
| 6 | 29521 |
| 7 | 227290 |
| 8 | 1865881 |
| 9 | 16239523 |
| 10 | 149142952 |
| 11 | 1439618143 |
| 12 | 14555631781 |
| 13 | 153700654036 |
| 14 | 1690684883191 |
| 15 | 19328770917499 |
| 16 | 229203640111870 |
| 17 | 2814018686591089 |
| 18 | 35711716110387589 |
| 19 | 467766675528462562 |