The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 44 |
| 3 | 404 |
| 4 | 414 |
| 5 | 424 |
| 6 | 434 |
| 7 | 444 |
| 8 | 454 |
| 9 | 464 |
| 10 | 474 |
| 11 | 484 |
| 12 | 494 |
| 13 | 4004 |
| 14 | 4114 |
| 15 | 4224 |
| 16 | 4334 |
| 17 | 4444 |
| 18 | 4554 |
| 19 | 4664 |
| 20 | 4774 |
| 21 | 4884 |
| 22 | 4994 |
| 23 | 40004 |
| 24 | 40104 |
| 25 | 40204 |
| 26 | 40304 |
| 27 | 40404 |
| 28 | 40504 |
| 29 | 40604 |
| 30 | 40704 |
| 31 | 40804 |
| 32 | 40904 |
| 33 | 41014 |
| 34 | 41114 |
| 35 | 41214 |
| 36 | 41314 |
| 37 | 41414 |
| 38 | 41514 |
| 39 | 41614 |
| 40 | 41714 |
| 41 | 41814 |
| 42 | 41914 |
[4,44,404,414,424,434,444,454,464,474,484,494, 4004,4114,4224,4334,4444,4554,4664,4774,4884,4994, 40004,40104,40204,40304,40404,40504,40604,40704, 40804,40904,41014,41114,41214,41314,41414,41514, 41614,41714,41814,41914] |