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

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

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

Patrick De Geest

Status

approved