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A291633 Numbers n such that it is possible to form a palindrome by concatenating all the binary strings from 1 to n. 0
1, 2, 3, 11, 20, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers that are not in the sequence include: 4, 6, 16, 18, 28, 30, 64, 66, 76, 78, 84, 86, 88, 90, ... as the total number of '0's and the total number of '1's in the binary expansion of 1 through n are both odd and thus cannot form a palindrome. - Chai Wah Wu, Jan 22 2018

LINKS

Table of n, a(n) for n=1..6.

EXAMPLE

Here are the first few solutions:

n=1: 1

n=2: 1|0|.1

n=3: 1.1|0|.11

n=11: 1010.1.1011.11.100.10|0|0.1001.111.10.110.101

n=20: 1101.10011.100.10100.111.1.1011.10001.1010.100|

00.10.101.1000.1110.1111.10010.1001.1100.110.11

n=22: 1000.1100.110.10100.10011.11.1010.1101.1011.1110.100|

00.10.1111.10110.1.10101.111.100.10010.101.1001.10001

CROSSREFS

Cf. A289469.

Sequence in context: A076201 A129668 A086791 * A004687 A097895 A298351

Adjacent sequences: A291630 A291631 A291632 * A291634 A291635 A291636

KEYWORD

nonn,base,more,hard

AUTHOR

Dmitry Kamenetsky, Sep 11 2017

STATUS

approved

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Last modified December 6 14:43 EST 2022. Contains 358644 sequences. (Running on oeis4.)