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A180737 a(n) is the largest n-digit square whose sum of digits is also a square. 2
9, 81, 961, 9025, 96721, 990025, 9966649, 99980001, 999761161, 9999400009, 99998250625, 999946000729, 9999989500176, 99999960000004, 999999455981824, 9999998600000049, 99999998724439696, 999999998000000001 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Daniel Mondot, Table of n, a(n) for n = 1..258

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 *)

CROSSREFS

Cf. A007953, A053057, A180738.

Sequence in context: A233021 A187122 A113361 * A068881 A104266 A061433

Adjacent sequences:  A180734 A180735 A180736 * A180738 A180739 A180740

KEYWORD

nonn,base,easy

AUTHOR

Daniel Mondot, Oct 08 2010

STATUS

approved

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Last modified October 26 14:28 EDT 2021. Contains 348267 sequences. (Running on oeis4.)