A394301 - OEIS

A394301

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

%I #8 Mar 16 2026 18:11:00

%S 0,1,1,2,2,1,1,3,3,2,2,2,2,3,3,3,3,3,3,2,2,4,4,4,4,3,3,3,3,3,3,5,5,4,

%T 4,4,4,4,4,4,4,3,3,5,5,5,5,5,5,5,5,4,4,4,4,4,4,6,6,6,6,5,5,5,5,5,5,5,

%U 5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,5,5,5,5,5,5,7,7,7,7,7,7,7,7,6

%N a(n) is the number of unit squares in the square lattice, divided by 4, that have 1 vertex strictly inside and 3 vertices 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="/A394301/b394301.txt">Table of n, a(n) for n = 0..10000</a>

%Y Cf. A005883, A393697, A394302, A394303.

%K nonn

%O 0,4

%A _Hugo Pfoertner_, Mar 15 2026