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A269387
Tree of Ludic sieve: a(0) = 1, a(1) = 2; after which, a(2n) = A269379(a(n)), a(2n+1) = 2*a(n).
8
1, 2, 3, 4, 5, 6, 9, 8, 7, 10, 15, 12, 19, 18, 21, 16, 11, 14, 27, 20, 35, 30, 33, 24, 31, 38, 51, 36, 49, 42, 45, 32, 13, 22, 39, 28, 65, 54, 57, 40, 59, 70, 87, 60, 79, 66, 69, 48, 55, 62, 111, 76, 125, 102, 105, 72, 85, 98, 123, 84, 109, 90, 93, 64, 17, 26, 63, 44, 95, 78, 81, 56, 113, 130, 159, 108, 139, 114, 117, 80
OFFSET
0,2
COMMENTS
Permutation of natural numbers obtained from the Ludic sieve. Note the indexing: Domain starts from 0, range from 1.
This sequence can be represented as a binary tree. Each left hand child is obtained by applying A269379 to the parent's contents, and each right hand child is obtained by doubling the parent's contents:
1
|
...................2...................
3 4
5......../ \........6 9......../ \........8
/ \ / \ / \ / \
/ \ / \ / \ / \
/ \ / \ / \ / \
7 10 15 12 19 18 21 16
11 14 27 20 35 30 33 24 31 38 51 36 49 42 45 32
etc.
Sequence A269385 is obtained from the mirror image of the same tree.
FORMULA
a(0) = 1, a(1) = 2; after which, a(2n) = A269379(a(n)), a(2n+1) = 2*a(n).
As a composition of other permutations:
a(n) = A269171(A252753(n)).
a(n) = A260741(A269377(n)).
PROG
(Scheme, with memoization-macro definec)
(definec (A269387 n) (cond ((<= n 2) (+ 1 n)) ((even? n) (A269379 (A269387 (/ n 2)))) (else (* 2 (A269387 (/ (- n 1) 2))))))
CROSSREFS
Inverse: A269388.
Cf. A003309 (left edge of the tree).
Cf. A269379.
Related permutations: A260741, A269171, A269385.
Cf. also A252753, A269377.
Sequence in context: A269866 A246375 A269865 * A207801 A340364 A324106
KEYWORD
nonn,tabf
AUTHOR
Antti Karttunen, Mar 01 2016
STATUS
approved