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A273185 Start with a(0) = 0. Thereafter a(n) is the number of m < n with the property that a(m) + n is a perfect square.

%I A273185 #18 May 25 2016 22:01:24
%S A273185 0,1,0,1,2,0,0,1,3,4,0,0,1,1,1,6,6,0,0,2,0,1,1,2,8,9,0,1,1,0,2,0,1,1,
%T A273185 4,12,12,2,0,0,1,1,0,2,0,2,1,7,15,17,0,0,2,0,0,1,1,1,2,0,2,1,10,19,22,
%U A273185 0,1,0,0,2,0,1,1,1,1,2,0,2,2,14
%N A273185 Start with a(0) = 0. Thereafter a(n) is the number of m < n with the property that a(m) + n is a perfect square.
%H A273185 Peter Kagey, <a href="/A273185/b273185.txt">Table of n, a(n) for n = 0..10000</a>
%e A273185 a(3) = 1 because 3 + a(1) is a perfect square.
%e A273185 a(4) = 2 because 4 + a(0) and 4 + a(2) are perfect squares.
%t A273185 a = {0}; Do[AppendTo[a, Count[a + n, k_ /; IntegerQ@ Sqrt@ k]], {n, 79}]; a (* _Michael De Vlieger_, May 25 2016 *)
%o A273185 (Java)
%o A273185 int n = 1000;
%o A273185 int[] terms = new int[n];
%o A273185 for (int i = 0; i < n; i++) {
%o A273185      for (int j = 0; j < i; j++) {
%o A273185           if (Math.sqrt(i+terms[j]) == Math.floor(Math.sqrt(i+terms[j]))) {
%o A273185                terms[i]++;
%o A273185           }
%o A273185      }
%o A273185      System.out.print(terms[i] + ", ");
%o A273185 }
%Y A273185 Cf. A273190.
%K A273185 easy,nonn
%O A273185 0,5
%A A273185 _Alec Jones_, May 17 2016