A230709 Union of even odious (cf. A128309) and evil numbers (cf. A001969).

0, 2, 3, 4, 5, 6, 8, 9, 10, 12, 14, 15, 16, 17, 18, 20, 22, 23, 24, 26, 27, 28, 29, 30, 32, 33, 34, 36, 38, 39, 40, 42, 43, 44, 45, 46, 48, 50, 51, 52, 53, 54, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 70, 71, 72, 74, 75, 76, 77, 78, 80, 82, 83, 84, 85, 86, 88

Offset

1,2

Comments

Apart from initial zero: numbers m, such that when mergesorting lists of length m, the maximal number of comparisons is odd: A003071(a(n+1)) = A230721(n).

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Index entries for sequences related to sorting

Formula

A010060(a(n)) * a(n) mod 2 = 0.

Mathematica

Complement[Range[0, m = 88], Select[Range[1, m, 2], OddQ[ Total[ IntegerDigits[#, 2]]]&]] (* Jean-François Alcover, Dec 15 2018 *)

Prog

(Haskell)
a230709 n = a230709_list !! (n-1)
a230709_list = filter (\x -> a010060 x * x `mod` 2 == 0) [0..]
(PARI) is(n)=if(hammingweight(n)%2, n%2==0, 1) \\ Charles R Greathouse IV, May 09 2016

Crossrefs

Cf. A092246 (complement).

Sequence in context: A068095 A064390 A229461 * A080671 A286608 A225736

Adjacent sequences: A230706 A230707 A230708 * A230710 A230711 A230712

Keyword

nonn,easy

Author

Reinhard Zumkeller, Oct 28 2013

Status

approved