A393696 - OEIS

A393696

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^2 + y^2 = n.

%I #10 Mar 15 2026 10:11:53

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

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

%U 3,5,5,5,4,2,2,4,4,4,4,4,2,4,4,6,6,2,5,5,5,3

%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^2 + y^2 = n.

%H Hugo Pfoertner, <a href="/A393696/b393696.txt">Table of n, a(n) for n = 0..10000</a>

%Y Cf. A004018, A393562, A393564, A393697, A393698.

%K nonn

%O 0,12

%A _Hugo Pfoertner_, Feb 28 2026