A118586 Numbers whose binary expansion contains group of at least two 1's followed by a nonempty group of 0's.

6, 12, 14, 24, 28, 30, 48, 56, 60, 62, 96, 112, 120, 124, 126, 192, 224, 240, 248, 252, 254, 384, 448, 480, 496, 504, 508, 510, 768, 896, 960, 992, 1008, 1016, 1020, 1022, 1536, 1792, 1920, 1984, 2016, 2032, 2040, 2044, 2046, 3072, 3584, 3840, 3968, 4032

Offset: 1

Author

Zak Seidov, May 07 2006

Keywords

• base
• nonn

Comments

All terms are even.

Examples

			4080_10 = 111111110000_2.
		

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A043569, A065442.

Programs

Mathematica

Sort[Flatten[Table[Sum[2^k,{k,k1,k2}],{k1,1,10},{k2,k1+1,11}]]]

Python

from itertools import count, islice
def agen(): # generator of terms
    for d in count(3):
        for i in range(2, d):
            yield int("1"*i + "0"*(d-i), 2)
print(list(islice(agen(), 50))) # Michael S. Branicky, Feb 20 2022

Formula

Sum_{n>=1} 1/a(n) = -1 + A065442. - Amiram Eldar, Feb 20 2022