OFFSET
1,2
COMMENTS
Terms of A048725, sorted.
See also A001969 for those divisible by x+1 (and obviously the present sequence is a subsequence of that one).
From Kevin Ryde, Jul 22 2022: (Start)
Integers with an even number of 1-bits at even positions, and an even number of 1-bits at odd positions, and so all k with A355487(k) = 0.
Among four integers 4*i ..4*i+3, exactly one is a term here so that a(n) can be calculated by appending two bits to n-1 to ensure the two 1-bit counts are even, so a(n) = 4*(n-1) + A355487(n-1).
(End)
PROG
(PARI) a(n) = n--; n<<2 + if(n, fold(bitxor, digits(n, 4))); \\ Kevin Ryde, Jul 01 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jack Zhang, Apr 28 2022
EXTENSIONS
More terms from David A. Corneth, Apr 28 2022
STATUS
approved