OFFSET
1,2
COMMENTS
Row n is the permutation of {1,...,2^n-1} which is the inverse of row n of A131987. See example for an illustration.
EXAMPLE
Row 4 of A131987 is obtained by reading the following binary tree, filled with numbers {1,...,15} in "storage order", from the leftmost to the rightmost number:
_____1_____
__2__ __3__
4 5 6 7
8 9 10 11 12 13 14 15
This yields the sequence p = (8, 4, 9, 2, 10, 5, 11, 1, 12, 6, 13, 3, 14, 7, 15) which is a permutation of (1, ..., 15). Row 4 of the present table yields the inverse permutation p' = (8, 4, 12, 2, 6, 10, 14, 1, 3, 5, 7, 9, 11, 13, 15), where p'(i) is the index of i in p, e.g. p'(3)=12 because 3 = p(12).
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
M. F. Hasler, Mar 04 2016
STATUS
approved