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

1,1

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.

Links

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

Example

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

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 *)

Prog

(Python)
from itertools import count, islice
def A161601_gen(startvalue=1): # generator of terms >= startvalue
    return filter(lambda n:n<int(bin(n)[-1:1:-1], 2), count(max(startvalue|1, 1), 2))
A161601_list = list(islice(A161601_gen(), 20)) # Chai Wah Wu, Jan 19 2023

Crossrefs

Cf. A030101, A006995, A161602, A161603.

Sequence in context: A129517 A287061 A359401 * A352480 A031406 A280993

Adjacent sequences: A161598 A161599 A161600 * A161602 A161603 A161604

Keyword

base,nonn

Author

Leroy Quet, Jun 14 2009

Extensions

Extended by Emeric Deutsch, Jun 28 2009

Edited by Jon E. Schoenfield, Feb 24 2019

Status

approved