%I
%S 4,9,17,26,37,51,66,83,102,122,145,170,197,225,256,288,323,359,397,
%T 437,479,523,569,617,667,718,772,828,885,945,1006,1069,1135,1202,1271,
%U 1342,1415,1490,1566,1645,1726,1808,1893,1979,2068,2158,2250,2344,2440,2539
%N Floor of Sum_{k=1..n} Sum_{m=1..k} (2*cosh(Pi*m/(2*k))  1).
%C Pi in the definition is A000796.
%C a(n) appears to oscillate near (n+1)^2.
%F a(n) = floor(2*Sum_{k=1..n} Sum_{m=1..k} cosh(Pi*m/(2*k))  A000217(n)).
%t Floor[N[Table[Sum[(2*Cos[Pi*I*i/(2j)]1),{j,1,k},{i,1,j}],{k,1,20}]]]
%K nonn
%O 1,1
%A _Daniel Tisdale_, Jun 06 2009
%E Variables redefined, sequence extended by _R. J. Mathar_, Aug 30 2010
