cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A071609 Squared radii of the spheres around (0,0,0) that contain record numbers of lattice points.

Original entry on oeis.org

1, 2, 5, 9, 14, 26, 41, 74, 89, 101, 146, 194, 269, 314, 341, 446, 614, 626, 689, 794, 854, 941, 1106, 1109, 1154, 1286, 1361, 1634, 1781, 1889, 2141, 2609, 2966, 3134, 3401, 3449, 3506, 4241, 4289, 4826, 5381, 5561, 6254, 7229, 7829, 8069, 8126
Offset: 1

Views

Author

Hugo Pfoertner, May 25 2002

Keywords

Comments

The number of lattice points (i,j,k) on the sphere around (0,0,0) with i^2 + j^2 + k^2 = a(n) is given by A071611(n).
Indices of records in A005875. - Daniel Suteu, Aug 13 2021

Crossrefs

A071611 Number of points (i,j,k) on the surface of a sphere around (0,0,0) with squared radius A071609(n).

Original entry on oeis.org

6, 12, 24, 30, 48, 72, 96, 120, 144, 168, 192, 240, 264, 312, 336, 384, 408, 432, 480, 504, 528, 552, 576, 600, 672, 696, 720, 768, 816, 864, 936, 1008, 1032, 1056, 1104, 1200, 1248, 1296, 1344, 1440, 1512, 1584, 1680, 1704, 1752, 1848, 1920, 2016
Offset: 1

Views

Author

Hugo Pfoertner, May 25 2002

Keywords

Comments

a(n) is the number of lattice points on a sphere around (0,0,0) with r^2 = A071609(n).

Examples

			A sphere with radius 1 has 6 lattice points on its surface, so a(1)=6. A sphere with r=sqrt(2) passes through 12 lattice points of the shape (1,1,0), so a(2)=12. A sphere with r=sqrt(5) passes through 24 lattice points with shape (2,1,0), so a(3)=24. A sphere with r=sqrt(9) passes through 6 lattice points of shape (3,0,0) and through 24 lattice points of shape (2,2,1), so a(4)=6+24=30.
		

Crossrefs

Formula

a(n) = A005875(A071609(n)). - Daniel Suteu, Aug 13 2021
Showing 1-2 of 2 results.