A053334 a(n) contains n digits (either '1' or '6') and is divisible by 2^n.

6, 16, 616, 1616, 11616, 111616, 6111616, 16111616, 616111616, 1616111616, 61616111616, 661616111616, 1661616111616, 61661616111616, 661661616111616, 6661661616111616, 66661661616111616, 666661661616111616

Offset

1,1

Links

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

Formula

a(n)=a(n-1)+10^(n-1)*(6-5*[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 a 6, if not then n-th term begins with a 1.

Mathematica

nxt[{n_, a_}]:={n+1, a+10^n (6-5*Mod[a/2^n, 2])}; NestList[nxt, {1, 6}, 20][[;; , 2]] (* Harvey P. Dale, Aug 20 2025 *)

Crossrefs

Cf. A023406, A050621, A050622, A035014.

Sequence in context: A118949 A303213 A264511 * A001143 A177365 A138490

Adjacent sequences: A053331 A053332 A053333 * A053335 A053336 A053337

Keyword

base,nonn

Author

Henry Bottomley, Mar 06 2000

Status

approved