A053377 a(n) contains n digits (either '3' or '8') and is divisible by 2^n.
8, 88, 888, 3888, 33888, 333888, 3333888, 83333888, 383333888, 3383333888, 33383333888, 833383333888, 8833383333888, 88833383333888, 888833383333888, 8888833383333888, 88888833383333888, 888888833383333888
Offset: 1
Links
- Ray Chandler, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
Flatten[Table[Select[FromDigits/@Tuples[{3,8},n],Divisible[#,2^n]&],{n,18}]] (* Harvey P. Dale, Dec 25 2015 *)
Formula
a(n)=a(n-1)+10^(n-1)*(8-5*[a(n-1)/2^(n-1) mod 2]) i.e. a(n) ends with a(n-1); if (n-1)-th term is divisible by 2^n then n-th term begins with an 8, if not then n-th term begins with a 3.