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A030151 Numbers n such that in n^2 the parity of digits alternates. 0
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

Table of n, a(n) for n=1..56.

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

Sequence in context: A275673 A026445 A279078 * A283455 A283364 A131617

Adjacent sequences:  A030148 A030149 A030150 * A030152 A030153 A030154

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

STATUS

approved

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Last modified August 18 03:16 EDT 2017. Contains 290682 sequences.