A180737 a(n) is the largest n-digit square whose sum of digits is also a square.
9, 81, 961, 9025, 96721, 990025, 9966649, 99980001, 999761161, 9999400009, 99998250625, 999946000729, 9999989500176, 99999960000004, 999999455981824, 9999998600000049, 99999998724439696, 999999998000000001
Offset: 1
Links
- Daniel Mondot, Table of n, a(n) for n = 1..258
Programs
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Mathematica
lnds[n_]:=Module[{s=Floor[Sqrt[10^n-1]]},While[!IntegerQ[Sqrt[Total[ IntegerDigits[ s^2]]]],s--];s^2]; Array[lnds,20] (* Harvey P. Dale, Mar 28 2013 *)