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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A331240 a(n) = number of triangles with integer sides i <= j <= k with diameter of circumcircle <= n. 3
0, 1, 3, 7, 14, 22, 34, 47, 67, 91, 117, 148, 187, 231, 281, 334, 400, 469, 548, 631, 727, 830, 943, 1062, 1202, 1339, 1490, 1657, 1833, 2024, 2226, 2434, 2662, 2905, 3155, 3427, 3712, 4014, 4321, 4653, 5005, 5362, 5749, 6141, 6558, 6994, 7440, 7911, 8408, 8917 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..50.

EXAMPLE

The diameter of the n-th circumcircle in the sorted list is D(n) = 2*sqrt(A331227(n)/A331228(n)). The list of diameters, rounded to 10^-4, starts: {1.1547, 2.0656, 2.3094, 3.0237, 3.0426, 3.1820, 3.4641, 4.0249, 4.0316, 4.1312, 4.1312, 4.3149, 4.6188, 5.0000, 5.0252, ...}.

a(1) = 0: 0 circles with D <= 1,

a(2) = 1: 1 circle (D = 1.1547) with 1 < D <= 2,

a(3) = 3: a(2) + 2 circles (D = 2.0656, 2.3094) with 2 < D <= 3,

a(4) = 7: a(3) + 4 circles (D = 3.02, 3.04, 3.18, 3.46) with 3 < D <= 4,

a(5) = 14: a(4) + 7 circles (D = 4.0249, ..., 5) with 4 < D <= 5.

CROSSREFS

Cf. A331227, A331228, A331229.

Sequence in context: A154772 A156859 A173209 * A146931 A176675 A213077

Adjacent sequences:  A331237 A331238 A331239 * A331241 A331242 A331243

KEYWORD

nonn,more

AUTHOR

Hugo Pfoertner, Jan 13 2020

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 January 19 16:16 EST 2021. Contains 340270 sequences. (Running on oeis4.)