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a(n) = -A338241(2*n) for any n >= 0.
3

%I #10 Oct 18 2020 22:32:41

%S 0,1,2,3,4,8,6,7,5,9,10,11,12,13,26,24,25,23,18,19,20,21,22,17,15,16,

%T 14,27,28,29,30,31,35,33,34,32,36,37,38,39,40,80,78,79,77,72,73,74,75,

%U 76,71,69,70,68,54,55,56,57,58,62,60,61,59,63,64,65,66,67

%N a(n) = -A338241(2*n) for any n >= 0.

%C This sequence is a self-inverse permutation of the nonnegative integers.

%H Rémy Sigrist, <a href="/A338242/b338242.txt">Table of n, a(n) for n = 0..6560</a>

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

%e a(7) = -A338241(14) = 7.

%o (PARI) b(n) = { if (n==0, return (0), my (d=n%3, m=n\3); if (d==0, 3*b(m), d==1, 1-3*b(m), 3*b(m)-1)) }

%o a(n) = -b(2*n)

%Y Cf. A338241, A338243.

%K nonn

%O 0,3

%A _Rémy Sigrist_, Oct 18 2020