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a(n) = n^2 - 5*floor(n/sqrt(5))^2.
1

%I #13 Sep 01 2012 02:36:07

%S 1,4,4,11,5,16,4,19,1,20,41,19,44,16,45,11,44,4,41,80,36,79,29,76,20,

%T 71,9,64,121,55,116,44,109,31,100,16,89,164,76,155,61,144,44,131,25,

%U 116,4,99,196,80,181,59,164,36,145,11,124,239,101,220,76,199,49,176,20,151

%N a(n) = n^2 - 5*floor(n/sqrt(5))^2.

%C a(n)=1 for n=A023039.

%H Zak Seidov, <a href="/A180498/b180498.txt">Table of n, a(n) for n = 1..1000</a>

%H Zak Seidov, <a href="/A180498/a180498.gif">Graphic of A180498</a>.

%e a(4)=11 since 4^2-5*floor(4/sqrt(5))^2=16-5=11.

%Y Cf. A023039, A082532.

%K nonn

%O 1,2

%A _Carmine Suriano_, Sep 08 2010