%I A143051
%S A143051 0,1,4,2,3,9,5,6,7,8,16,10,11,12,13,14,15,25,17,18,19,20,21,22,23,24,36,
%T A143051 26,27,28,29,30,31,32,33,34,35,49,37,38,39,40,41,42,43,44,45,46,47,48,
%U A143051 64,50,51,52,53,54,55,56,57,58,59,60,61,62,63,81,65,66,67,68,69,70,71
%N A143051 Smallest number not occurring earlier and smaller than the largest square 
               so far, the next square if no such number exists.
%C A143051 Permutation of the natural numbers, inverse: A143052;
%C A143051 A143053(n) = a(a(n));
%C A143051 a(A000290(n)) = A005563(n-1);
%C A143051 a(A002522(n)) = A000290(n+1);
%C A143051 for n>1: GCD(a(n^2),a(n^2+1)) = A050873(A000290(n),A002522(n)) =
%C A143051 A022998(n+1).
%H A143051 <a href="Sindx_Per.html#IntegerPermutation">Index entries for sequences 
               that are permutations of the natural numbers</a>
%F A143051 a(n) = if n=0 then 0 else if n=1+k^2 then n+2*k else n-1.
%Y A143051 Sequence in context: A143054 A016512 A026246 this_sequence A120240 A102629 
               A082361
%Y A143051 Adjacent sequences: A143048 A143049 A143050 this_sequence A143052 A143053 
               A143054
%K A143051 nonn
%O A143051 0,3
%A A143051 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 20 2008