A255239 Alternating row sums of triangle A255238.

1, 1, 2, 3, 3, 4, 3, 5, 4, 7, 6, 8, 7, 10, 6, 9, 6, 11, 9, 14, 11, 15, 10, 15, 11, 14, 11, 18, 14, 19, 14, 18, 13, 20, 15, 23, 16, 25, 21, 24, 19, 23, 16, 27, 20, 28, 21, 30, 22, 27, 22, 31, 25, 34, 27, 35, 24, 35, 26, 32, 29, 36, 26, 39, 28

Offset: 0

Author

Wolfdieter Lang, Mar 12 2015

Keywords

• nonn
• easy

Comments

See A255238 for a Gauss' circle problem comment and a link.

Crossrefs

Cf. A255238.

Formula

a(n) = sum((-1)^m*T(n, m), m = 0..n), n >= 0, with T(n, m) = A255238(n, m) = 1 + floor(sqrt(n^2 - m^2)).