A140900 A nonnegative integer n is included if the binary representation of n and the digit-reversal (with leading 0's) of the binary representation of n do not have any 1's in the same position.

0, 2, 4, 8, 10, 12, 16, 18, 24, 32, 34, 36, 38, 40, 42, 48, 52, 56, 64, 66, 68, 70, 80, 82, 96, 100, 112, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 160, 162, 168, 170, 176, 178, 192, 196, 200, 204, 208, 212, 224, 232, 240, 256, 258, 260, 262, 264

Offset

1,2

Comments

All terms of this sequence are even.

Number of terms less than or equal to 10^n: 1, 5, 26, 162, 1045, 5976, 38980, 249229, 1416583, 9381238, ..., . - Robert G. Wilson v, Aug 04 2008

Number of terms < 2^k: 1, 2, 3, 6, 18, 27, 54, 81,... (A038754). - T. D. Noe, Apr 09 2009

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Example

36 in binary is 100100. The digit-reversal (with leading 0's) of this is 001001. These binary representations have no 1's in the same location (i.e., they can be added in binary without any carries). So 36 is in this sequence.

Mathematica

fQ[n_] := Block[{id = IntegerDigits[n, 2]}, Max@ Union[id + Reverse@ id] < 2]; Select[2 Range[0, 134], fQ@# &] (* Robert G. Wilson v, Aug 04 2008 *)

Prog

(PARI) is(n) = my (b=if (n, binary(n), [0])); vecmax(b+Vecrev(b))<=1 \\ Rémy Sigrist, Jun 11 2022

Crossrefs

A035928 is a subsequence.

Sequence in context: A346502 A321580 A224694 * A166936 A166245 A276623

Adjacent sequences: A140897 A140898 A140899 * A140901 A140902 A140903

Keyword

base,nonn

Author

Leroy Quet, Jul 24 2008

Extensions

More terms from Robert G. Wilson v, Aug 04 2008

Status

approved