cp's OEIS Frontend

A360648 Fully multiplicative with a(A027697(k)) = A027699(k) and a(A027699(k)) = A027697(k) for any k > 0.

%I A360648 #9 Feb 16 2023 05:06:31
%S A360648 1,3,2,9,7,6,5,27,4,21,17,18,23,15,14,81,11,12,29,63,10,51,13,54,49,
%T A360648 69,8,45,19,42,43,243,34,33,35,36,53,87,46,189,71,30,31,153,28,39,83,
%U A360648 162,25,147,22,207,37,24,119,135,58,57,89,126,101,129,20,729
%N A360648 Fully multiplicative with a(A027697(k)) = A027699(k) and a(A027699(k)) = A027697(k) for any k > 0.
%C A360648 In other words, we replace odious prime numbers with evil prime numbers and vice versa.
%C A360648 This sequence is a self-inverse permutation of the positive integers.
%H A360648 Rémy Sigrist, <a href="/A360648/a360648.png">Scatterplot of (n, a(n)) such that n, a(n) <= 100000</a>
%H A360648 Rémy Sigrist, <a href="/A360648/a360648.gp.txt">PARI program</a>
%H A360648 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%e A360648 For n = 84:
%e A360648 - 82 = 2^2 * 3 * 7,
%e A360648 - a(2) = a(A027697(1)) = A027699(1) = 3,
%e A360648 - a(3) = a(A027699(1)) = A027697(1) = 2,
%e A360648 - a(7) = a(A027697(2)) = A027699(2) = 5,
%e A360648 - so a(84) = 3^2 * 2 * 5 = 90.
%o A360648 (PARI) See Links section.
%Y A360648 Cf. A061898, A027697, A027699, A341090.
%K A360648 nonn,base,mult
%O A360648 1,2
%A A360648 _Rémy Sigrist_, Feb 15 2023