A161602 Positive integers k that are greater than the value of the reversal of k's binary representation.

2, 4, 6, 8, 10, 12, 13, 14, 16, 18, 20, 22, 24, 25, 26, 28, 29, 30, 32, 34, 36, 38, 40, 41, 42, 44, 46, 48, 49, 50, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 81, 82, 84, 86, 88, 89, 90, 92, 94, 96, 97, 98, 100, 101, 102, 104, 105, 106, 108, 109

Offset

1,1

Comments

By "reversal" of k's binary representation, it is meant: write k in binary, reverse the order of its digits, and read the result as a binary value.

This sequence contains all the positive even integers.

Links

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

Example

29 in binary is 11101. Its digital reversal is 10111, which is 23 in decimal. Since 29 > 23, 29 is in this sequence.

Mathematica

Select[Range[109], # > IntegerReverse[#, 2] &] (* Michael De Vlieger, Apr 07 2021 *)

Prog

(PARI) isok(k) = k > fromdigits(Vecrev(binary(k)), 2); \\ Michel Marcus, Apr 06 2021
(Python)
from itertools import count, islice
def A161602_gen(startvalue=1): # generator of terms >= startvalue
    return filter(lambda n:n>int(bin(n)[-1:1:-1], 2), count(max(startvalue, 1)))
A161602_list = list(islice(A161602_gen(), 20)) # Chai Wah Wu, Jan 19 2023

Crossrefs

Cf. A030101, A006995, A161601, A161603 (odd terms).

Cf. A071590 (using decimal reversal).

Sequence in context: A365453 A365984 A301454 * A359496 A356066 A285591

Adjacent sequences: A161599 A161600 A161601 * A161603 A161604 A161605

Keyword

base,nonn

Author

Leroy Quet, Jun 14 2009

Extensions

More terms from Max Alekseyev, Sep 11 2009

Status

approved