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

1,1

Links

Ray Chandler, Table of n, a(n) for n = 1..1000

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.

Mathematica

Table[Select[FromDigits/@Tuples[{1, 8}, n], Divisible[#, 2^n]&], {n, 20}]// Flatten (* Harvey P. Dale, Aug 20 2017 *)

Crossrefs

Cf. A023411, A050621, A050622, A035014.

Sequence in context: A043043 A003492 A368919 * A053377 A053378 A062185

Adjacent sequences: A053373 A053374 A053375 * A053377 A053378 A053379

Keyword

base,nonn

Author

Henry Bottomley, Mar 06 2000

Status

approved