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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. 4
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 (list; graph; refs; listen; history; text; internal format)
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 A343680

Adjacent sequences:  A079235 A079236 A079237 * A079239 A079240 A079241

KEYWORD

base,nonn

AUTHOR

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

STATUS

approved

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Last modified November 29 11:46 EST 2021. Contains 349416 sequences. (Running on oeis4.)