A328012 Numbers whose binary representations start and end with 1 and contain an even number of zeros between.

1, 3, 7, 9, 15, 19, 21, 25, 31, 33, 39, 43, 45, 51, 53, 57, 63, 67, 69, 73, 79, 81, 87, 91, 93, 97, 103, 107, 109, 115, 117, 121, 127, 129, 135, 139, 141, 147, 149, 153, 159, 163, 165, 169, 175, 177, 183, 187, 189, 195, 197, 201, 207, 209, 215, 219, 221, 225

Offset

1,2

Comments

Odd members of A059010. - Robert Israel, Nov 30 2019

Links

Jonathan Frech, Table of n, a(n) for n = 1..10000

Maple

q:= n-> (l-> l[1]=1 and add(1-i, i=l)::even)(Bits[Split](n)):
select(q, [$1..300])[];  # Alois P. Heinz, Oct 04 2019

Mathematica

{1}~Join~Select[Range[3, 225, 2], EvenQ@ DigitCount[#, 2, 0] &] (* Michael De Vlieger, Oct 05 2019 *)

Prog

(PARI) ok(n)={n%2 && hammingweight((2<<logint(n, 2)) - 1 - n)%2==0} \\ Andrew Howroyd, Oct 01 2019
(Python)
n, a = 0, 1
while n < 58:
    aa, k = a, 0
    while aa > 0:
        d, aa = aa%2, aa//2
        if d == 0:
            k = k+1
    if k%2 == 0:
        n = n+1
        print(n, a)
    a = a+2 # A.H.M. Smeets, Oct 04 2019

Crossrefs

Cf. A023416, A059010.

Sequence in context: A187108 A026175 A026139 * A292911 A119681 A197625

Adjacent sequences: A328009 A328010 A328011 * A328013 A328014 A328015

Keyword

nonn,base

Author

Justin Clifton, Oct 01 2019

Extensions

More terms from Alois P. Heinz, Oct 04 2019

Status

approved