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A231431
Evil squares.
6
0, 9, 36, 144, 169, 225, 441, 576, 676, 729, 900, 1369, 1764, 2025, 2209, 2304, 2704, 2809, 2916, 3249, 3600, 3721, 3969, 4761, 5329, 5476, 6561, 6889, 7056, 8100, 8649, 8836, 9216, 9801, 10816, 11025, 11236, 11449, 11664, 11881, 12321, 12996, 13225, 14161, 14400, 14884, 15129, 15876, 17689, 18769, 19044, 19881, 21316, 21904
OFFSET
1,2
COMMENTS
Numbers n^2 such that A159918(n) is even.
Intersection of A000290 and A001969.
LINKS
FORMULA
Conjecture: a(n) ~ 4n^2. - Charles R Greathouse IV, Nov 20 2013
EXAMPLE
36 is in the sequence because 36 = 6^2 and 36 in base 2 is 100100, having an even number of 1's.
MATHEMATICA
Select[Range[0, 150]^2, EvenQ[DigitCount[#, 2, 1]]&] (* Harvey P. Dale, Nov 23 2015 *)
PROG
(PARI) is(n)=hammingweight(n)%2==0 && issquare(n) \\ Charles R Greathouse IV, Nov 20 2013
CROSSREFS
Sequence in context: A023872 A034557 A285241 * A264515 A002063 A285674
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
Corrected and extended by Harvey P. Dale, Nov 23 2015
STATUS
approved