login
Where the n-th nonprime occurs in the nonprime EKG sequence A240024.
4

%I #24 Jul 05 2014 11:12:55

%S 1,2,3,4,7,5,6,10,8,11,9,12,15,13,14,18,21,16,20,17,22,25,23,19,24,28,

%T 26,29,27,30,33,31,32,43,34,37,35,36,40,44,38,45,39,46,49,47,41,48,52,

%U 50,42,51,53,56,54,60,55,57,64,58,59,74,62,65,61,63,71

%N Where the n-th nonprime occurs in the nonprime EKG sequence A240024.

%C A240024(a(n)) = A018252(n);

%C a permutation of the natural numbers with inverse A238862: a(A238862(n))=A238862(a(n))=n.

%H Reinhard Zumkeller, <a href="/A239965/b239965.txt">Table of n, a(n) for n = 1..10000</a>

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

%o (Haskell)

%o import Data.List (elemIndex); import Data.Maybe (fromJust)

%o a239965 = (+ 1) . fromJust . (`elemIndex` a240024_list) . a018252

%Y Cf. A239943 (fixed points).

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Apr 30 2014