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

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, 28, 27, 31, 32, 29, 30, 35, 36, 33, 34, 38, 37, 41, 42, 39, 40, 44, 43, 46, 45, 48, 47, 50, 49, 53, 54, 51, 52, 56, 55, 58, 57, 60, 59, 62, 61, 65, 66, 63, 64, 68

Offset: 1

Author

Reinhard Zumkeller, Aug 04 2015

Keywords

• nonn

Comments

The permutation is self-inverse: a(a(n)) = n;

by definition there are no fixed points.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A010051, A002808, A260933.

Programs

Haskell

import Data.List (delete)
a260822 n = a260822_list !! (n-1)
a260822_list = f 1 [1..] where
   f x zs = g zs where
     g (y:ys) = if y /= x && a010051' (x + y) == 0
                   then y : f (x + 1) (delete y zs) else g ys