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Complement of A147875.
1

%I #10 Oct 12 2024 16:37:32

%S 1,2,3,5,6,7,8,9,10,11,12,14,15,16,17,18,19,20,21,22,23,24,25,26,28,

%T 29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,47,48,49,50,51,52,

%U 53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85

%N Complement of A147875.

%F (See the Mathematica code.)

%F a(n) = n+floor(sqrt(2n/5)) if 2n > floor(sqrt(2n/5))(5*floor(sqrt(2n/5))+1) and a(n) = n+floor(sqrt(2n/5))-1 otherwise. - _Chai Wah Wu_, Oct 12 2024

%t a=5/2; b=3/2;

%t F[n_]:=a*n^2+b*n;

%t R[n_]:=(n/a+((b-1)/(2a))^2)^(1/2);

%t G[n_]:=n-1+Ceiling[R[n]-(b-1)/(2a)];

%t Table[F[n], {n,60}]

%t Table[G[n], {n,100}]

%o (Python)

%o from math import isqrt

%o def A183298(n): return n+(m:=isqrt((k:=n<<1)//5))-(k<=m*(5*m+1)) # _Chai Wah Wu_, Oct 12 2024

%Y Cf. A147875.

%K nonn

%O 1,2

%A _Clark Kimberling_, Jan 03 2011