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.

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, 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, 3, 5, 5, 5, 4, 2, 2, 4, 4, 4, 4, 4, 2, 4, 4, 6, 6, 2, 5, 5, 5, 3

Offset

0,12

Links

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

Crossrefs

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

Sequence in context: A290531 A376629 A206442 * A137581 A156311 A270740

Adjacent sequences: A393693 A393694 A393695 * A393697 A393698 A393699

Keyword

nonn

Author

Hugo Pfoertner, Feb 28 2026

Status

approved