A267710 Number of unit triangular lattice cells enclosed by origin centered circle of diameter n.

0, 6, 6, 24, 24, 54, 60, 96, 114, 150, 180, 216, 258, 324, 348, 426, 450, 540, 564, 666, 720, 804, 870, 954, 1056, 1134, 1230, 1344, 1416, 1542, 1614, 1752, 1842, 1974, 2100, 2208, 2346, 2478, 2628, 2778, 2898, 3084, 3180, 3378, 3474, 3684, 3822, 4002, 4176, 4356

Offset

1,2

Comments

As n -> infinity, lim a(n)/(n^2) -> Pi/sqrt(3).

Links

Luca Petrone, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A093602 (Pi/sqrt(3)).

Sequence in context: A253100 A247640 A255470 * A306896 A087236 A341267

Adjacent sequences: A267707 A267708 A267709 * A267711 A267712 A267713

Keyword

easy,nonn

Author

Luca Petrone, Jan 19 2016

Status

approved