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A260822 Lexicographically smallest permutation of the natural numbers, such that a(n)+n is a composite number and a(n) != n.

%I A260822 #30 Aug 04 2015 20:44:46
%S A260822 3,4,1,2,7,8,5,6,11,12,9,10,14,13,17,18,15,16,20,19,23,24,21,22,26,25,
%T A260822 28,27,31,32,29,30,35,36,33,34,38,37,41,42,39,40,44,43,46,45,48,47,50,
%U A260822 49,53,54,51,52,56,55,58,57,60,59,62,61,65,66,63,64,68
%N A260822 Lexicographically smallest permutation of the natural numbers, such that a(n)+n is a composite number and a(n) != n.
%C A260822 The permutation is self-inverse: a(a(n)) = n;
%C A260822 by definition there are no fixed points.
%H A260822 Reinhard Zumkeller, <a href="/A260822/b260822.txt">Table of n, a(n) for n = 1..10000</a>
%H A260822 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%o A260822 (Haskell)
%o A260822 import Data.List (delete)
%o A260822 a260822 n = a260822_list !! (n-1)
%o A260822 a260822_list = f 1 [1..] where
%o A260822    f x zs = g zs where
%o A260822      g (y:ys) = if y /= x && a010051' (x + y) == 0
%o A260822                    then y : f (x + 1) (delete y zs) else g ys
%Y A260822 Cf. A010051, A002808, A260933.
%K A260822 nonn
%O A260822 1,1
%A A260822 _Reinhard Zumkeller_, Aug 04 2015