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A235331 Numbers with odious squares. 3

%I

%S 1,2,4,5,7,8,9,10,11,14,16,17,18,19,20,22,23,25,28,29,31,32,33,34,35,

%T 36,38,39,40,41,43,44,46,49,50,51,55,56,58,59,62,64,65,66,67,68,70,71,

%U 72,75,76,77,78,79,80,82,85,86,87,88,89,91,92,95,97,98,100

%N Numbers with odious squares.

%C Numbers that are sqrt(odious squares).

%H Vincenzo Librandi, <a href="/A235331/b235331.txt">Table of n, a(n) for n = 1..2600</a>

%F a(n) = sqrt(A235001(n)).

%e 1 = sqrt(A235001(1)) = sqrt(1).

%e 2 = sqrt(A235001(2)) = sqrt(4).

%e 4 = sqrt(A235001(3)) = sqrt(16).

%e 5 = sqrt(A235001(4)) = sqrt(25).

%t Select[Range[200], OddQ[DigitCount[#^2, 2][[1]]] &] (* _Vincenzo Librandi_, Jan 31 2018 *)

%o (MAGMA) [n : n in [0..130] |IsOdd(&+Intseq(n^2, 2))]; // _Vincenzo Librandi_, Jan 31 2018

%o (PARI) isok(n) = (hammingweight(n^2) % 2) == 1; \\ _Michel Marcus_, Jan 31 2018

%Y Cf. A235001, A194991.

%K nonn,easy

%O 1,2

%A _Gerasimov Sergey_, Jan 06 2014

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Last modified May 17 08:40 EDT 2021. Contains 343966 sequences. (Running on oeis4.)