A053313 a(n) contains n digits (either '2' or '9') and is divisible by 2^n.

2, 92, 992, 2992, 92992, 292992, 2292992, 22292992, 222292992, 2222292992, 22222292992, 922222292992, 9922222292992, 29922222292992, 929922222292992, 9929922222292992, 99929922222292992, 999929922222292992

Offset

1,1

Links

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

Formula

a(n)=a(n-1)+10^(n-1)*(2+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 a 2, if not then n-th term begins with a 7.

Mathematica

Select[Flatten[Table[FromDigits/@Tuples[{2, 9}, n], {n, 18}]], Divisible[ #, 2^IntegerLength[ #]]&] (* Harvey P. Dale, Feb 07 2015 *)

Crossrefs

Cf. A023400, A050621, A050622, A035014.

Sequence in context: A116162 A116293 A030985 * A226404 A166825 A348852

Adjacent sequences: A053310 A053311 A053312 * A053314 A053315 A053316

Keyword

base,nonn

Author

Henry Bottomley, Mar 06 2000

Status

approved