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A269172 Permutation of natural numbers: a(1) = 1, a(2n) = 2*a(n), a(2n+1) = A250469(a(A269380(2n+1))). 10


%S 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,25,20,21,22,19,24,23,26,

%T 27,28,29,30,49,32,33,34,35,36,31,50,39,40,37,42,41,44,45,38,43,48,55,

%U 46,51,52,47,54,121,56,57,58,77,60,53,98,63,64,65,66,59,68,69,70,61,72,169,62,75,100,67,78,85,80,81

%N Permutation of natural numbers: a(1) = 1, a(2n) = 2*a(n), a(2n+1) = A250469(a(A269380(2n+1))).

%H Antti Karttunen, <a href="/A269172/b269172.txt">Table of n, a(n) for n = 1..2244</a>

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%F a(1) = 1, then after for even n, a(n) = 2*a(n/2), and for odd n, A250469(a(A269380(n))).

%F a(1) = 1, for n > 1, a(n) = A083221(A260738(n), a(A260739(n))).

%F As a composition of other permutations:

%F a(n) = A252755(A269386(n)).

%F a(n) = A252753(A269388(n)).

%F Other identities. For all n >= 1:

%F A000035(a(n)) = A000035(n). [This permutation preserves the parity of n.]

%F a(A003309(n)) = A008578(n). [Maps Ludic numbers to noncomposites.]

%o (Scheme, two versions, both using memoization-macro definec)

%o (definec (A269172 n) (cond ((<= n 1) n) ((even? n) (* 2 (A269172 (/ n 2)))) (else (A250469 (A269172 (A269380 n))))))

%o (definec (A269172 n) (if (<= n 1) n (A083221bi (A260738 n) (A269172 (A260739 n))))) ;; Code for A083221bi given in A083221.

%Y Inverse: A269171.

%Y Cf. A000035, A003309, A008578, A083221, A250469, A260738, A260739, A269380.

%Y Related or similar permutations: A260741, A260742, A269356, A269358, A255422.

%Y Cf. also A269394 (a(3n)/3) and A269396.

%Y Differs from A255408 for the first time at n=38, where a(38) = 50, while A255408(38) = 38.

%K nonn

%O 1,2

%A _Antti Karttunen_, Mar 03 2016

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Last modified July 27 13:36 EDT 2021. Contains 346306 sequences. (Running on oeis4.)