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 A030151 Numbers k such that in k^2 the parity of digits alternates. 7
 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; text; internal format)
 OFFSET 1,3 LINKS Giovanni Resta, Table of n, a(n) for n = 1..10000 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]] (* Harvey P. Dale, May 12 2011 *) CROSSREFS Cf. A030152, A030153, A030154, A030159. Sequence in context: A279078 A308627 A330500 * A307360 A283455 A283364 Adjacent sequences:  A030148 A030149 A030150 * A030152 A030153 A030154 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified June 29 07:33 EDT 2022. Contains 354910 sequences. (Running on oeis4.)