A079238 Numbers n in which the last K digits of n form an integer divisible by K^2, for K = 1, 2, ..., M, where M is the number of digits in n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 108, 144, 180, 216, 252, 288, 324, 360, 396, 432, 468, 504, 540, 576, 612, 648, 684, 720, 756, 792, 828, 864, 900, 936, 972, 1072, 1216, 1360, 1504, 1648

Offset

1,2

Comments

The terms satisfying the definition become increasingly rare as the number of their digits increases. There are only 214 such terms up to 1 million, the last of which is 990000. [From Harvey P. Dale, Apr 10 2012]

Links

Harvey P. Dale, Table of n, a(n) for n = 1..200

Example

a(84)=4864 because 4 is divisible by 1^2, 64 by 2^2, 864 by 3^2, 4864 by 4^2.

Mathematica

idkQ[n_]:=Module[{idn=IntegerDigits[n]}, And@@Table[Divisible[ FromDigits[ Take[idn, -i]], i^2], {i, Length[idn]}]]; Select[Range[1700], idkQ] (* Harvey P. Dale, Apr 10 2012 *)

Crossrefs

Sequence in context: A343744 A064653 A130588 * A079042 A193455 A356349

Adjacent sequences: A079235 A079236 A079237 * A079239 A079240 A079241

Keyword

base,nonn

Author

Sudipta Das (juitech(AT)vsnl.net), Feb 03 2003

Status

approved