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A360396
Intersection of A356133 and A360392.
4
7, 11, 17, 20, 25, 29, 32, 38, 43, 47, 53, 56, 62, 67, 71, 74, 79, 83, 89, 92, 97, 101, 104, 110, 115, 119, 122, 127, 131, 137, 140, 146, 151, 155, 161, 164, 169, 173, 176, 182, 187, 191, 197, 200, 206, 211, 215, 218, 223, 227, 233, 236, 242, 247, 251, 257
OFFSET
1,1
COMMENTS
This is the third of four sequences that partition the positive integers. Starting with a general overview, suppose that u = (u(n)) and v = (v(n)) are increasing sequences of positive integers. Let u' and v' be their complements, and assume that the following four sequences are infinite:
(1) u ^ v = intersection of u and v (in increasing order);
(2) u ^ v';
(3) u' ^ v;
(4) u' ^ v'.
Every positive integer is in exactly one of the four sequences. The limiting densities of these four sequences are 4/9, 2/9, 2/9, and 1/9, respectively.
For A360396, u, v, u', v', are sequences obtained from the Thue-Morse sequence, A026430, as follows:
u = A026530 = (1,3,5,6,8,9,10, 12, ... ) = partial sums of A026430
u' = A356133 = (2,4,7,11,13,17, 20, ... ) = complement of u
v = u + 1 = A285954, except its initial 1
v' = complement of v.
EXAMPLE
(1) u ^ v = (3, 5, 8, 10, 12, 14, 16, 18, 21, 23, 26, 28, 30, 33, ...) = A360394
(2) u ^ v' = (1, 6, 9, 15, 19, 24, 27, 31, 36, 42, 45, 51, 55, 60, ...) = A360395
(3) u' ^ v = (7, 11, 17, 20, 25, 29, 32, 38, 43, 47, 53, 56, 62, ...) = A360396
(4) u' ^ v' = (2, 4, 13, 22, 34, 40, 49, 58, 64, 76, 85, 94, 106, ...) = A360397
MATHEMATICA
z = 400;
u = Accumulate[1 + ThueMorse /@ Range[0, z]]; (* A026430 *)
u1 = Complement[Range[Max[u]], u]; (* A356133 *)
v = u + 2 ; (* A360392 *)
v1 = Complement[Range[Max[v]], v]; (* A360393 *)
Intersection[u, v] (* A360394 *)
Intersection[u, v1] (* A360395 *)
Intersection[u1, v] (* A360396 *)
Intersection[u1, v1] (* A360397 *)
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Feb 05 2023
STATUS
approved