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%I #13 Mar 12 2013 04:09:31
%S 16,196,1156,12996,104976,1069156,10010896,102292996,1000077376,
%T 10064904976,100003942756,1002069069156,10000040096656,
%U 100063290010896,1000000467910656,10002022902292996,100000005048995076,1000063249000077376,10000000024233296896
%N Smallest n-digit square such that no number made by chopping off a group of one or more digits from the left is a square.
%C Ending in 6 is a must for a number to be part of this sequence
%e a(5) cannot be 104^2 = 10816 because 16 (the last 2 digits) makes a square. 114^2 = 12996 qualifies.
%t bad[n_] := Block[{q = n^2, p = 10}, While[p < q, If[IntegerQ@Sqrt@Mod[q, p], Break[], p *= 10]]; p < q]; a[n_] := Block[{k = Ceiling[10^((n - 1)/2)]}, While[bad@k, k++]; k^2]; a /@ Range[2, 20] (* _Giovanni Resta_, Mar 11 2013 *)
%K nonn,base
%O 2,1
%A _J. Lowell_, Nov 24 2010
%E a(12)-a(20) from _Giovanni Resta_, Mar 11 2013
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