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A030151
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Numbers n such that in n^2 the parity of digits alternates.
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0
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0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 19, 23, 26, 27, 31, 36, 69, 74, 81, 84, 96, 111, 113, 119, 127, 137, 181, 187, 204, 237, 264, 269, 273, 277, 281, 296, 311, 384, 404, 426, 461, 463, 539, 574, 584, 606, 661, 673, 677, 689, 726, 736, 764, 819
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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MATHEMATICA
| upto=2000; tfs=Flatten[Table[{True, False}, {Ceiling[IntegerLength[ upto]]}]]; altparQ[n_]:= Module[{n2=n^2}, MemberQ[Partition[ tfs, IntegerLength[n2], 1], EvenQ/@IntegerDigits[n2]]]; Join[{0}, Select[Range[upto], altparQ]] (* From Harvey P. Dale, May 12 2011 *)
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CROSSREFS
| Sequence in context: A011867 A008725 A026445 * A131617 A005577 A072966
Adjacent sequences: A030148 A030149 A030150 * A030152 A030153 A030154
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KEYWORD
| nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com)
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