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n-1+ceiling(3(n+2)/5); complement of A183864.
1

%I #10 Jun 13 2015 00:53:42

%S 1,4,8,13,19,27,36,46,57,69,83,98,114,131,149,169,190,212,235,259,285,

%T 312,340,369,399,431,464,498,533,569,607,646,686,727,769,813,858,904,

%U 951,999,1049,1100,1152,1205,1259,1315,1372,1430,1489,1549,1611,1674,1738,1803,1869,1937,2006,2076,2147,2219

%N n-1+ceiling(3(n+2)/5); complement of A183864.

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,1,-2,1).

%F a(n)=n-1+ceiling(3(n+2)/5).

%F a(n) = 2 a(n-1) -a(n-2) +a(n-5) -2 a(n-6) +a(n-7). - R. J. Mathar, Mar 11 2012

%t a=5/3; b=0;

%t Table[n+Floor[(a*n+b)^(1/2)],{n,100}]

%t Table[n-1+Ceiling[(n*n-b)/a],{n,60}]

%Y Cf. A183864.

%K nonn,easy

%O 1,2

%A _Clark Kimberling_, Jan 07 2011