A394303 - OEIS

%I #9 Mar 16 2026 18:10:51

%S 0,0,0,1,1,0,0,2,2,1,1,1,1,2,2,2,2,2,2,1,1,3,3,3,3,2,2,2,2,2,2,4,4,3,

%T 3,3,3,3,3,3,3,2,2,4,4,4,4,4,4,4,4,3,3,3,3,3,3,5,5,5,5,4,4,4,4,4,4,4,

%U 4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,4,4,4,4,4,4,6,6,6,6,6,6,6,6,5

%N a(n) is the number of unit squares in the square lattice, divided by 4, that have 3 vertices strictly inside and 1 vertex strictly outside the circle (x-1/2)^2 + (y-1/2)^2 = n, i.e., the circle centered at the deep hole.

%H Hugo Pfoertner, <a href="/A394303/b394303.txt">Table of n, a(n) for n = 0..10000</a>

%Y Cf. A005883, A393696, A394301, A394302.

%K nonn

%O 0,8

%A _Hugo Pfoertner_, Mar 15 2026