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%I #10 Oct 23 2023 17:25:18
%S 1,2,3,6,7,11,12,16,18,22,23,29,30,34,37,42,43,49,50,56,59,63,64,72,
%T 74,78,81,87,88,96,97,103,106,110,113,122,123,127,130,138,139,147,148,
%U 154,159,163,164,174,176,182,185,191,192,200,203,211,214,218,219,231,232
%N a(n) = Sum_{k=1..floor(n/2)} floor(n/k) for n >= 2, with a(1) = 1.
%e a(6) = floor(6/1) + floor(6/2) + floor(6/3) = 11.
%t Table[If[n == 1, 1, Sum[Floor[n/i], {i, Floor[n/2]}]], {n, 80}] (* _Wesley Ivan Hurt_, Nov 26 2020 *)
%o (Python)
%o from math import isqrt
%o def A075995(n): return -(s:=isqrt(n))**2+(sum(n//k for k in range(1,s+1))<<1)-(n+1>>1) if n>1 else 1 # _Chai Wah Wu_, Oct 23 2023
%Y a(n) = A006218(n) - floor((n+1)/2) for n >= 2.
%K nonn,easy
%O 1,2
%A _Clark Kimberling_, Sep 28 2002
%E Name corrected by _Wesley Ivan Hurt_, Nov 26 2020