

A228008


The smallest ndigit number whose first k digits are divisible by k^2 for k = 1..n.


0




OFFSET

1,2


COMMENTS

There are 7 terms in the sequence and the 7digit number 6480005 is the last number to satisfy the requirements.


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

There are nine onedigit numbers divisible by 1 and smallest is 1 so a(1)=1.
For twodigit numbers, the second digit must make it divisible by 2^2, which gives 12 as the smallest to satisfy the requirement, so a(2)=12.


MATHEMATICA

a = Table[j, {j, 9}]; r = 2; t = {}; While[! a == {}, n = Length[a]; nmin = First[a]; k = 1; b = {}; While[! k > n, z0 = a[[k]]; Do[z = 10*z0 + j; If[Mod[z, r*r] == 0, b = Append[b, z]], {j, 0, 9}]; k++]; AppendTo[t, nmin]; a = b; r++]; t


CROSSREFS

Cf. A079042.
Sequence in context: A343769 A159736 A004991 * A101602 A264896 A062199
Adjacent sequences: A228005 A228006 A228007 * A228009 A228010 A228011


KEYWORD

nonn,base,fini,full


AUTHOR

Shyam Sunder Gupta, Aug 08 2013


STATUS

approved



