A053376 a(n) contains n digits (either '1' or '8') and is divisible by 2^n.
8, 88, 888, 1888, 81888, 181888, 8181888, 18181888, 118181888, 8118181888, 88118181888, 888118181888, 8888118181888, 88888118181888, 888888118181888, 1888888118181888, 81888888118181888, 181888888118181888
Offset: 1
Links
- Ray Chandler, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
Table[Select[FromDigits/@Tuples[{1,8},n],Divisible[#,2^n]&],{n,20}]// Flatten (* Harvey P. Dale, Aug 20 2017 *)
Formula
a(n)=a(n-1)+10^(n-1)*(8-7*[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 1.