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A171781
Numbers for which the second bit of the binary expansion is equal to the last bit.
2
2, 3, 4, 7, 8, 10, 13, 15, 16, 18, 20, 22, 25, 27, 29, 31, 32, 34, 36, 38, 40, 42, 44, 46, 49, 51, 53, 55, 57, 59, 61, 63, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125
OFFSET
1,1
COMMENTS
Note that A005843 INTERSECT A171781 = A171757. This is an example of two sequences which both have a limiting density, but whose intersection does not.
LINKS
EXAMPLE
10 is a term since its binary representation is 1010 and both its second and last bits are 0. - Amiram Eldar, Sep 01 2020
MATHEMATICA
Select[Range[2, 125], (d = IntegerDigits[#, 2])[[2]] == d[[-1]] &] (* Amiram Eldar, Sep 01 2020 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Oct 12 2010
STATUS
approved