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A361146
a(n) is the sibling of n in the infinite binary tree underlying A361144.
2
2, 1, 9, 5, 4, 7, 6, 10, 3, 8, 14, 31, 18, 11, 17, 19, 15, 13, 16, 21, 20, 23, 22, 26, 32, 24, 28, 27, 30, 29, 12, 25, 34, 33, 41, 37, 36, 39, 38, 42, 35, 40, 133, 46, 50, 44, 49, 51, 47, 45, 48, 53, 52, 56, 59, 54, 76, 60, 55, 58, 62, 61, 64, 63, 66, 65, 73
OFFSET
1,1
COMMENTS
This sequence is a self-inverse permutation of the positive integers with no fixed point.
FORMULA
a(A361144(2*n)) = A361144(2*n-1).
a(A361144(2*n-1)) = A361144(2*n).
EXAMPLE
The infinite binary tree underlying A361144 starts as follows:
176
---------------------------------
43 133
----------------- -----------------
12 31 57 76
--------- --------- --------- ---------
3 9 13 18 25 32 35 41
----- ----- ----- ----- ----- ----- ----- -----
1 2 4 5 6 7 8 10 11 14 15 17 16 19 20 21
.
So a(1) = 2 and a(2) = 1, a(4) = 5 and a(5) = 4, etc.,
a(3) = 9 and a(9) = 3, a(13) = 18 and a(18) = 13, etc.,
a(12) = 31 and a(31) = 12, a(57) = 76 and a(76) = 57,
a(43) = 133 and a(133) = 43.
PROG
(PARI) See Links section.
CROSSREFS
Sequence in context: A298521 A177972 A011136 * A067304 A103876 A133174
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Mar 02 2023
STATUS
approved