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A260430 Involution of natural numbers: a(1) = 1, a(A257803(1+n)) = A257804(a(n)), a(A257804(n)) = A257803(1+a(n)), where A257803 and A257804 give the positions of odd and even terms in A233271, the infinite trunk of inverted binary beanstalk. 5

%I

%S 1,4,12,2,30,7,6,74,19,21,18,3,172,52,54,49,48,11,9,383,10,128,125,32,

%T 36,132,31,119,118,5,27,24,812,314,89,25,283,92,275,76,86,85,83,290,

%U 75,267,266,17,16,68,60,14,724,15,227,1675,219,659,207,51,64,599,216,61,232,583,174,50,204,210,201,193,208,8,45,40,1574,612,173,569,595,159,43

%N Involution of natural numbers: a(1) = 1, a(A257803(1+n)) = A257804(a(n)), a(A257804(n)) = A257803(1+a(n)), where A257803 and A257804 give the positions of odd and even terms in A233271, the infinite trunk of inverted binary beanstalk.

%H Antti Karttunen, <a href="/A260430/b260430.txt">Table of n, a(n) for n = 1..4453</a>

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

%F a(1) = 1; for n > 1, if A257800(n) = 0 [when n is one of the terms of A257804] a(n) = A257803(1+a(A257808(n))), otherwise [when n is one of the terms of A257803] a(n) = A257804(a(A257807(n)-1)).

%o (Scheme, with memoizing macro definec)

%o (definec (A260430 n) (cond ((<= n 1) n) ((zero? (A257800 n)) (A257803 (+ 1 (A260430 (A257808 n))))) (else (A257804 (A260430 (+ -1 (A257807 n)))))))

%Y Cf. A257800, A257803, A257804, A257807, A257808.

%Y Cf. also A233271, A257806.

%Y Related permutations: A260431 - A260434.

%K nonn

%O 1,2

%A _Antti Karttunen_, Jul 27 2015

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Last modified December 16 04:22 EST 2019. Contains 330013 sequences. (Running on oeis4.)