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A231431 Evil squares. 6

%I

%S 0,9,36,144,169,225,441,576,676,729,900,1369,1764,2025,2209,2304,2704,

%T 2809,2916,3249,3600,3721,3969,4761,5329,5476,6561,6889,7056,8100,

%U 8649,8836,9216,9801,10816,11025,11236,11449,11664,11881,12321,12996,13225,14161,14400,14884,15129,15876,17689,18769,19044,19881,21316,21904

%N Evil squares.

%C Numbers n^2 such that A159918(n) is even.

%C Intersection of A000290 and A001969.

%H Amiram Eldar, <a href="/A231431/b231431.txt">Table of n, a(n) for n = 1..10000</a>

%F Conjecture: a(n) ~ 4n^2. - _Charles R Greathouse IV_, Nov 20 2013

%e 36 is in the sequence because 36 = 6^2 and 36 in base 2 is 100100, having an even number of 1's.

%t Select[Range[0,150]^2,EvenQ[DigitCount[#,2,1]]&] (* _Harvey P. Dale_, Nov 23 2015 *)

%o (PARI) is(n)=hammingweight(n)%2==0 && issquare(n) \\ _Charles R Greathouse IV_, Nov 20 2013

%Y Cf. A000290, A125498.

%K nonn,base,easy

%O 1,2

%A _Juri-Stepan Gerasimov_, Nov 20 2013

%E Corrected and extended by _Harvey P. Dale_, Nov 23 2015

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Last modified May 12 10:54 EDT 2021. Contains 343821 sequences. (Running on oeis4.)