OFFSET
1,1
COMMENTS
a(13)=0, a(14)=0 because there are no 13- or 14-digit numbers which satisfy the requirements. The sequence is infinite.
LINKS
Shyam Sunder Gupta, Table of n, a(n) for n = 1..150
EXAMPLE
There are ten one-digit numbers divisible by 1 and largest is 9 so a(1)=9.
For two-digit numbers, the second digit must make it divisible by 2^2, which gives 96 as the largest to satisfy the requirement, so a(2)=96.
MATHEMATICA
a = Table[j, {j, 0, 9}]; r = 2; s2 = 10; t = a; xs = {Last[a]}; While[! a == {}, n = Length[a]; k = 1; b = {}; While[! k > n, z0 = a[[k]]; Do[z = 10^(r - 1)*j + z0; If[Mod[z, r*r] == 0 && r < 25, b = Append[b, z]; t = Append[t, z]], {j, 0, 9}]; k++]; s = Union[t]; s1 = Length[s]; If[r < 25, If[s1 > s2, xs = Append[xs, Last[s]], xs = Append[xs, 0]]]; s2 = s1; a = b; r++]; xs
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Shyam Sunder Gupta, Aug 08 2013
STATUS
approved