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 | 1 |
| 2 | 4 |
| 3 | 23 |
| 4 | 136 |
| 5 | 707 |
| 6 | 3312 |
| 7 | 14527 |
| 8 | 61264 |
| 9 | 252515 |
| 10 | 1027192 |
| 11 | 4147343 |
| 12 | 16674984 |
| 13 | 66887875 |
| 14 | 267960544 |
| 15 | 1072726271 |
| 16 | 4292804896 |
| 17 | 17175281987 |
| 18 | 68709777768 |
| 19 | 274857460111 |
| 20 | 1099468636600 |
| 21 | 4397956334051 |
| 22 | 17591997301264 |
| 23 | 70368349913663 |
| 24 | 281474154627696 |
| 25 | 1125898195567267 |