A161601 Positive integers k that are less than the value of the reversal of k's representation in binary.

11, 19, 23, 35, 37, 39, 43, 47, 55, 67, 69, 71, 75, 77, 79, 83, 87, 91, 95, 103, 111, 131, 133, 135, 137, 139, 141, 143, 147, 149, 151, 155, 157, 159, 163, 167, 171, 173, 175, 179, 183, 187, 191, 199, 203, 207, 215, 223, 239, 259, 261, 263, 265, 267, 269, 271

Offset: 1

Author

Leroy Quet, Jun 14 2009

Keywords

• base
• nonn

Comments

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

This sequence contains only odd integers.

Examples

			37 = 100101_2; its digital reversal is 101001_2 = 41. Since 37 < 41, 37 is in this sequence.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A030101, A006995, A161602, A161603.

Programs

Maple

a := proc (n) local n2, sz, rv: n2 := convert(n, base, 2): sz := nops(n2): rv := add(n2[j]*2^(sz-j), j = 1 .. sz): if n < rv then n else end if end proc; seq(a(n), n = 1 .. 280); # Emeric Deutsch, Jun 28 2009

Mathematica

Select[Range[300],FromDigits[Reverse[IntegerDigits[#,2]],2]>#&] (* Harvey P. Dale, Mar 19 2016 *)

Python

from itertools import count, islice
def A161601_gen(startvalue=1): # generator of terms >= startvalue
    return filter(lambda n:nA161601_list = list(islice(A161601_gen(),20)) # Chai Wah Wu, Jan 19 2023

Extensions

Extended by Emeric Deutsch, Jun 28 2009

Edited by Jon E. Schoenfield, Feb 24 2019