A393697 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^2 + y^2 = n.

0, 0, 0, 1, 1, 0, 2, 2, 0, 1, 1, 3, 3, 0, 2, 2, 2, 2, 2, 3, 1, 3, 3, 3, 3, 0, 2, 4, 4, 2, 4, 4, 2, 3, 1, 3, 3, 3, 5, 5, 3, 2, 4, 4, 4, 2, 4, 4, 4, 4, 2, 5, 3, 3, 5, 5, 5, 5, 3, 5, 5, 2, 4, 4, 4, 2, 6, 6, 4, 6, 6, 6, 4, 3, 3, 5, 5, 5, 5, 5, 3, 5, 5, 7, 7, 2, 6, 6, 6, 4

Offset

0,7

Links

Hugo Pfoertner, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A004018, A393562, A393564, A393696, A393698.

Sequence in context: A293112 A306910 A112185 * A192062 A172371 A279006

Adjacent sequences: A393694 A393695 A393696 * A393698 A393699 A393700

Keyword

nonn

Author

Hugo Pfoertner, Feb 28 2026

Status

approved