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A030157
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Even numbers k such that in k^2 the parity of digits alternates.
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5
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0, 2, 4, 6, 16, 26, 36, 74, 84, 96, 204, 264, 296, 384, 404, 426, 574, 584, 606, 726, 736, 764, 874, 884, 964, 1464, 1584, 1596, 1704, 2036, 2074, 2084, 2184, 2916, 2926, 2964, 3306, 3536, 3764, 3816, 4116, 4264, 4306, 5684, 5726, 5736, 5874
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OFFSET
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1,2
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LINKS
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MAPLE
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alp:= proc(n) local L, d;
L:= convert(n, base, 10);
d:= nops(L);
if d::even then L:= L + map(op, [[0, 1]$(d/2)]) else L:= L + map(op, [[0, 1]$((d-1)/2), [0]]) fi;
nops(convert(L mod 2, set))=1
end proc:
select(t -> alp(t^2), [seq(i, i=0..10000, 2)]); # Robert Israel, Aug 15 2018
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MATHEMATICA
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id[n_]:=IntegerDigits[n^2]; t={}; Do[If[Length[id[n]]==1, AppendTo[t, n], If[Union[Abs[Differences[Boole/@EvenQ[id[n]]]]]=={1}, AppendTo[t, n]]], {n, 0, 6000, 2}]; t (* Vincenzo Librandi, Aug 15 2018 *)
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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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