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 | 4 |
| 2 | 35 |
| 3 | 446 |
| 4 | 2827 |
| 5 | 13686 |
| 6 | 59859 |
| 7 | 250198 |
| 8 | 1023347 |
| 9 | 4140830 |
| 10 | 16663627 |
| 11 | 66867438 |
| 12 | 267922683 |
| 13 | 1072654438 |
| 14 | 4292666147 |
| 15 | 17175010598 |
| 16 | 68709242467 |
| 17 | 274856398542 |
| 18 | 1099466524251 |
| 19 | 4397952122110 |
| 20 | 17591988892331 |
| 21 | 70368333113174 |