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

1,1

Links

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

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.

Mathematica

Flatten[Table[Select[FromDigits/@Tuples[{3, 8}, n], Divisible[#, 2^n]&], {n, 18}]] (* Harvey P. Dale, Dec 25 2015 *)

Crossrefs

Cf. A023412, A050621, A050622, A035014.

Sequence in context: A003492 A368919 A053376 * A053378 A062185 A053379

Adjacent sequences: A053374 A053375 A053376 * A053378 A053379 A053380

Keyword

base,nonn

Author

Henry Bottomley, Mar 06 2000

Status

approved