Number of n-digit 7-smooth numbers (A002473).

Terms

a(0) =0a(1) =9a(2) =36a(3) =95a(4) =197a(5) =356a(6) =579a(7) =882a(8) =1272a(9) =1767a(10) =2381a(11) =3113a(12) =3984a(13) =5002a(14) =6187a(15) =7545a(16) =9081a(17) =10815a(18) =12759a(19) =14927a(20) =17323a(21) =19960a(22) =22853a(23) =26015a(24) =29458a(25) =33188a(26) =37222a(27) =41568a(28) =46245a(29) =51254