A247647 Binary numbers that begin and end with 1 and do not contain two adjacent zeros.

1, 11, 101, 111, 1011, 1101, 1111, 10101, 10111, 11011, 11101, 11111, 101011, 101101, 101111, 110101, 110111, 111011, 111101, 111111, 1010101, 1010111, 1011011, 1011101, 1011111, 1101011, 1101101, 1101111, 1110101, 1110111, 1111011, 1111101, 1111111, 10101011, 10101101, 10101111, 10110101, 10110111, 10111011, 10111101

Offset

1,2

Links

Chai Wah Wu, Table of n, a(n) for n = 1..1000

Formula

a(n) = A007088(A247648(n)).

Mathematica

With[{upto=500}, Map[FromDigits, Select[IntegerString[Range[1, upto, 2], 2], StringFreeQ[#, "00"]&]]] (* Paolo Xausa, Dec 06 2023 *)

Prog

(Python)
A247647_list = [int(bin(n)[2:]) for n in range(1, 10**5) if n % 2 and not '00' in bin(n)]
# Chai Wah Wu, Sep 25 2014
(Haskell)
a247647 = a007088 . a247648  -- Reinhard Zumkeller, Sep 25 2014

Crossrefs

See A247648 for the decimal equivalents.

Cf. A007088, A247649, A253085.

Sequence in context: A057148 A076289 A350346 * A240602 A117697 A305395

Adjacent sequences: A247644 A247645 A247646 * A247648 A247649 A247650

Keyword

nonn,base

Author

N. J. A. Sloane, Sep 25 2014

Status

approved