login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A267710 Number of unit triangular lattice cells enclosed by origin centered circle of diameter n. 2
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 (list; graph; refs; listen; history; text; internal format)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)