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A102832
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Number of n-digit squares which contain the string "666" but not "6666".
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0
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0, 0, 0, 0, 0, 0, 3, 21, 78, 302, 1139, 4156, 14791, 52529, 183565, 635691, 2183533, 7314869, 25303217
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OFFSET
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1,7
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LINKS
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MATHEMATICA
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fQ[n_] := StringPosition[ ToString[n^2], "666"] != {} && StringPosition[ ToString[n^2], "6666"] == {}; t = Table[0, {20}]; Do[ If[ fQ[n], t[[ Ceiling[ Log[10, n^2]] + 1]]++ ], {n, 3162277661}]; t (* Robert G. Wilson v, Mar 10 2005 *)
t6[digs_]:=Module[{a=Floor[Sqrt[10^(digs-1)]], b=Floor[ Sqrt[ 10^digs]]}, Count[ Range[a, b]^2, _?(SequenceCount[IntegerDigits[#], {6, 6, 6}]> 0&&SequenceCount[IntegerDigits[#], {6, 6, 6, 6}]==0&)]]; Table[ t6[n], {n, 20}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 26 2021 *)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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