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A020471 as a simple table

na(n)
17
279
397
4797
5977
6997
777797
877977
977999
1079777
1179979
1279997
1379999
1497777
15777977
16777979
17779797
18797977
19799979
20799999
21999979
227777997
237779979
247779997
257797799
267797997
277799797
287799999
297977779
307977797
317977799
327977997

[7,79,97,797,977,997,77797,77977,77999,79777,
 79979,79997,79999,97777,777977,777979,779797,
 797977,799979,799999,999979,7777997,7779979,
 7779997,7797799,7797997,7799797,7799999,7977779,
 7977797,7977799,7977997]