A053338 a(n) contains n digits (either '6' or '9') and is divisible by 2^n.

6, 96, 696, 9696, 69696, 669696, 6669696, 96669696, 696669696, 9696669696, 69696669696, 969696669696, 9969696669696, 69969696669696, 969969696669696, 9969969696669696, 99969969696669696, 999969969696669696, 9999969969696669696, 99999969969696669696, 699999969969696669696

Offset

1,1

Links

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

Formula

a(n+1) = a(n) + 10^n * (6 + 3*[a(n)/2^n 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 a 6, if not then n-th term begins with a 9.

Mathematica

Table[Select[FromDigits/@Tuples[{6, 9}, n], Mod[#, 2^n]==0&], {n, 20}]//Flatten (* Harvey P. Dale, Sep 15 2023 *)

Crossrefs

Cf. A023410, A050621, A050622, A035014 (same with digits 3 & 4), A053312 - A053337 (digits 1,2 through 6,7) and A053376 - A053380 (8,1 through 8,9).

Sequence in context: A179058 A303212 A226549 * A389822 A115400 A279868

Adjacent sequences: A053335 A053336 A053337 * A053339 A053340 A053341

Keyword

base,nonn

Author

Henry Bottomley, Mar 06 2000

Status

approved