cp's OEIS Frontend

A094510 Smallest number distinct from n, not occurring earlier and having in binary representation exactly as many ones as n.

%I A094510 #15 Nov 30 2014 03:29:20
%S A094510 2,1,5,8,3,9,11,4,6,12,7,10,14,13,23,32,18,17,21,24,19,25,15,20,22,28,
%T A094510 29,26,27,39,47,16,34,33,37,40,35,41,30,36,38,44,45,42,43,51,31,65,50,
%U A094510 49,46,56,54,53,59,52,58,57,55,71,62,61,95,128,48,68,69,66,67,73,60
%N A094510 Smallest number distinct from n, not occurring earlier and having in binary representation exactly as many ones as n.
%C A094510 a(a(n))=n: a self-inverse permutation of natural numbers.
%H A094510 Paul Tek, <a href="/A094510/b094510.txt">Table of n, a(n) for n = 1..10000</a>
%H A094510 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%H A094510 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%o A094510 (Haskell)
%o A094510 import Data.List (delete)
%o A094510 a094510 n = a094510_list !! (n-1)
%o A094510 a094510_list = f 1 [1..] where
%o A094510    f x zs = g zs where
%o A094510      g (y:ys) = if y /= x && a000120 y == wt
%o A094510                    then y : f (x + 1) (delete y zs) else g ys
%o A094510      wt = a000120 x
%o A094510 -- _Reinhard Zumkeller_, Nov 23 2014
%Y A094510 Cf. A094511, A007088, A000120.
%K A094510 nonn
%O A094510 1,1
%A A094510 _Reinhard Zumkeller_, May 06 2004